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  <div class="section" id="extension-using-the-c-c-languages">
<h1>Extension using the C/C++ languages<a class="headerlink" href="#extension-using-the-c-c-languages" title="Permalink to this headline">¶</a></h1>
<p>We can extend the Ring Virtual Machine (RingVM) by adding new functions written in the C programming language or C++.
The RingVM comes with many functions written in C that we can call like any Ring function.</p>
<p>We can extend the language by writing new functions then rebuilding the RingVM again, or we can create shared
library (DLL/So) file to extend the RingVM without the need to rebuild it.</p>
<p>The Ring language source code comes with two files to add new modules to the RingVM, ring_ext.h and ring_ext.c</p>
<div class="section" id="ring-ext-h">
<span id="index-0"></span><h2>ring_ext.h<a class="headerlink" href="#ring-ext-h" title="Permalink to this headline">¶</a></h2>
<p>The file ring_ext.h contains constants that we can change to include/exclude modules during the build process.</p>
<div class="highlight-C"><div class="highlight"><pre><span class="cp">#ifndef ringext_h</span>
<span class="cp">#define ringext_h</span>
<span class="cm">/* Constants */</span>
<span class="cp">#define RING_VM_LISTFUNCS       1</span>
<span class="cp">#define RING_VM_REFMETA         1</span>
<span class="cp">#define RING_VM_MATH            1</span>
<span class="cp">#define RING_VM_FILE            1</span>
<span class="cp">#define RING_VM_OS              1</span>
<span class="cp">#define RING_VM_MYSQL           1</span>
<span class="cp">#define RING_VM_ODBC            1</span>
<span class="cp">#define RING_VM_OPENSSL         1</span>
<span class="cp">#define RING_VM_CURL            1</span>
<span class="cp">#define RING_VM_DLL             1</span>
<span class="cp">#endif</span>
</pre></div>
</div>
</div>
<div class="section" id="ring-ext-c">
<span id="index-1"></span><h2>ring_ext.c<a class="headerlink" href="#ring-ext-c" title="Permalink to this headline">¶</a></h2>
<p>The file ring_ext.c check constants defined in ring_ext.h before calling the start-up function in each module.</p>
<p>Each module contains a function that register the module functions in the RingVM.</p>
<div class="highlight-C"><div class="highlight"><pre><span class="cp">#include &quot;ring.h&quot;</span>

<span class="kt">void</span> <span class="nf">ring_vm_extension</span> <span class="p">(</span> <span class="n">RingState</span> <span class="o">*</span><span class="n">pRingState</span> <span class="p">)</span>
<span class="p">{</span>
        <span class="cm">/* Reflection and Meta-programming */</span>
        <span class="cp">#if RING_VM_REFMETA</span>
                <span class="n">ring_vm_refmeta_loadfunctions</span><span class="p">(</span><span class="n">pRingState</span><span class="p">);</span>
        <span class="cp">#endif</span>
        <span class="cm">/* List Functions */</span>
        <span class="cp">#if RING_VM_LISTFUNCS</span>
                <span class="n">ring_vm_listfuncs_loadfunctions</span><span class="p">(</span><span class="n">pRingState</span><span class="p">);</span>
        <span class="cp">#endif</span>
        <span class="cm">/* Math */</span>
        <span class="cp">#if RING_VM_MATH</span>
                <span class="n">ring_vm_math_loadfunctions</span><span class="p">(</span><span class="n">pRingState</span><span class="p">);</span>
        <span class="cp">#endif</span>
        <span class="cm">/* File */</span>
        <span class="cp">#if RING_VM_FILE</span>
                <span class="n">ring_vm_file_loadfunctions</span><span class="p">(</span><span class="n">pRingState</span><span class="p">);</span>
        <span class="cp">#endif</span>
        <span class="cm">/* OS */</span>
        <span class="cp">#if RING_VM_OS</span>
                <span class="n">ring_vm_os_loadfunctions</span><span class="p">(</span><span class="n">pRingState</span><span class="p">);</span>
        <span class="cp">#endif</span>
        <span class="cm">/* MySQL */</span>
        <span class="cp">#if RING_VM_MYSQL</span>
                <span class="n">ring_vm_mysql_loadfunctions</span><span class="p">(</span><span class="n">pRingState</span><span class="p">);</span>
        <span class="cp">#endif</span>
        <span class="cm">/* ODBC */</span>
        <span class="cp">#if RING_VM_ODBC</span>
                <span class="n">ring_vm_odbc_loadfunctions</span><span class="p">(</span><span class="n">pRingState</span><span class="p">);</span>
        <span class="cp">#endif</span>
        <span class="cm">/* OPENSSL */</span>
        <span class="cp">#if RING_VM_OPENSSL</span>
                <span class="n">ring_vm_openssl_loadfunctions</span><span class="p">(</span><span class="n">pRingState</span><span class="p">);</span>
        <span class="cp">#endif</span>
        <span class="cm">/* CURL */</span>
        <span class="cp">#if RING_VM_CURL</span>
                <span class="n">ring_vm_curl_loadfunctions</span><span class="p">(</span><span class="n">pRingState</span><span class="p">);</span>
        <span class="cp">#endif</span>
        <span class="cm">/* DLL */</span>
        <span class="cp">#if RING_VM_DLL</span>
                <span class="n">ring_vm_dll_loadfunctions</span><span class="p">(</span><span class="n">pRingState</span><span class="p">);</span>
        <span class="cp">#endif</span>
<span class="p">}</span>
</pre></div>
</div>
</div>
<div class="section" id="module-organization">
<span id="index-2"></span><h2>Module Organization<a class="headerlink" href="#module-organization" title="Permalink to this headline">¶</a></h2>
<p>Each module starts by include the ring header file (ring.h).
This files contains the Ring API that we can use to extend the RingVM.</p>
<p>Each module comes with a function to register the module functions in the RingVM
The registration is done by using ring_vm_funcregister() function.</p>
<p>The ring_vm_funcregister() function takes two parameters, the first is the function name
that will be used by Ring programs to call the function. The second parameter is the
function pointer in the C program.</p>
<p>for example, the ring_vmmath.c module contains the next code to register the module functions</p>
<div class="highlight-C"><div class="highlight"><pre><span class="cp">#include &quot;ring.h&quot;</span>

<span class="kt">void</span> <span class="nf">ring_vm_math_loadfunctions</span> <span class="p">(</span> <span class="n">RingState</span> <span class="o">*</span><span class="n">pRingState</span> <span class="p">)</span>
<span class="p">{</span>
        <span class="n">ring_vm_funcregister</span><span class="p">(</span><span class="s">&quot;sin&quot;</span><span class="p">,</span><span class="n">ring_vm_math_sin</span><span class="p">);</span>
        <span class="n">ring_vm_funcregister</span><span class="p">(</span><span class="s">&quot;cos&quot;</span><span class="p">,</span><span class="n">ring_vm_math_cos</span><span class="p">);</span>
        <span class="n">ring_vm_funcregister</span><span class="p">(</span><span class="s">&quot;tan&quot;</span><span class="p">,</span><span class="n">ring_vm_math_tan</span><span class="p">);</span>
        <span class="n">ring_vm_funcregister</span><span class="p">(</span><span class="s">&quot;asin&quot;</span><span class="p">,</span><span class="n">ring_vm_math_asin</span><span class="p">);</span>
        <span class="n">ring_vm_funcregister</span><span class="p">(</span><span class="s">&quot;acos&quot;</span><span class="p">,</span><span class="n">ring_vm_math_acos</span><span class="p">);</span>
        <span class="n">ring_vm_funcregister</span><span class="p">(</span><span class="s">&quot;atan&quot;</span><span class="p">,</span><span class="n">ring_vm_math_atan</span><span class="p">);</span>
        <span class="n">ring_vm_funcregister</span><span class="p">(</span><span class="s">&quot;atan2&quot;</span><span class="p">,</span><span class="n">ring_vm_math_atan2</span><span class="p">);</span>
        <span class="n">ring_vm_funcregister</span><span class="p">(</span><span class="s">&quot;sinh&quot;</span><span class="p">,</span><span class="n">ring_vm_math_sinh</span><span class="p">);</span>
        <span class="n">ring_vm_funcregister</span><span class="p">(</span><span class="s">&quot;cosh&quot;</span><span class="p">,</span><span class="n">ring_vm_math_cosh</span><span class="p">);</span>
        <span class="n">ring_vm_funcregister</span><span class="p">(</span><span class="s">&quot;tanh&quot;</span><span class="p">,</span><span class="n">ring_vm_math_tanh</span><span class="p">);</span>
        <span class="n">ring_vm_funcregister</span><span class="p">(</span><span class="s">&quot;exp&quot;</span><span class="p">,</span><span class="n">ring_vm_math_exp</span><span class="p">);</span>
        <span class="n">ring_vm_funcregister</span><span class="p">(</span><span class="s">&quot;log&quot;</span><span class="p">,</span><span class="n">ring_vm_math_log</span><span class="p">);</span>
        <span class="n">ring_vm_funcregister</span><span class="p">(</span><span class="s">&quot;log10&quot;</span><span class="p">,</span><span class="n">ring_vm_math_log10</span><span class="p">);</span>
        <span class="n">ring_vm_funcregister</span><span class="p">(</span><span class="s">&quot;ceil&quot;</span><span class="p">,</span><span class="n">ring_vm_math_ceil</span><span class="p">);</span>
        <span class="n">ring_vm_funcregister</span><span class="p">(</span><span class="s">&quot;floor&quot;</span><span class="p">,</span><span class="n">ring_vm_math_floor</span><span class="p">);</span>
        <span class="n">ring_vm_funcregister</span><span class="p">(</span><span class="s">&quot;fabs&quot;</span><span class="p">,</span><span class="n">ring_vm_math_fabs</span><span class="p">);</span>
        <span class="n">ring_vm_funcregister</span><span class="p">(</span><span class="s">&quot;pow&quot;</span><span class="p">,</span><span class="n">ring_vm_math_pow</span><span class="p">);</span>
        <span class="n">ring_vm_funcregister</span><span class="p">(</span><span class="s">&quot;sqrt&quot;</span><span class="p">,</span><span class="n">ring_vm_math_sqrt</span><span class="p">);</span>
        <span class="n">ring_vm_funcregister</span><span class="p">(</span><span class="s">&quot;unsigned&quot;</span><span class="p">,</span><span class="n">ring_vm_math_unsigned</span><span class="p">);</span>
        <span class="n">ring_vm_funcregister</span><span class="p">(</span><span class="s">&quot;decimals&quot;</span><span class="p">,</span><span class="n">ring_vm_math_decimals</span><span class="p">);</span>
        <span class="n">ring_vm_funcregister</span><span class="p">(</span><span class="s">&quot;murmur3hash&quot;</span><span class="p">,</span><span class="n">ring_vm_math_murmur3hash</span><span class="p">);</span>
<span class="p">}</span>
</pre></div>
</div>
<div class="admonition tip">
<p class="first admonition-title">Tip</p>
<p class="last">Remember that the function ring_vm_math_loadfunctions() will be called by the
ring_vm_extension() function (in the ring_ext.c file).</p>
</div>
</div>
<div class="section" id="function-structure">
<span id="index-3"></span><h2>Function Structure<a class="headerlink" href="#function-structure" title="Permalink to this headline">¶</a></h2>
<p>Each module function may contains the next steps</p>
<p>1 - Check Parameters Count</p>
<p>2 - Check Parameters Type</p>
<p>3 - Get Parameters Values</p>
<p>4 - Execute Code/Call Functions</p>
<p>5 - Return Value</p>
<p>The structure is very similar to any function (Input - Process - Output)
But here we will use the Ring API for the steps 1,2,3 and 5.</p>
</div>
<div class="section" id="check-parameters-count">
<span id="index-4"></span><h2>Check Parameters Count<a class="headerlink" href="#check-parameters-count" title="Permalink to this headline">¶</a></h2>
<p>We can check the parameters count using the RING_API_PARACOUNT macro.</p>
<p>We can compare RING_API_PARACOUNT with any numeric value using == or != operators.</p>
<p>Example:</p>
<div class="highlight-C"><div class="highlight"><pre><span class="k">if</span> <span class="p">(</span> <span class="n">RING_API_PARACOUNT</span> <span class="o">!=</span> <span class="mi">1</span> <span class="p">)</span> <span class="p">{</span>
        <span class="cm">/* code */</span>
<span class="p">}</span>
</pre></div>
</div>
<p>Example:</p>
<div class="highlight-C"><div class="highlight"><pre><span class="k">if</span> <span class="p">(</span> <span class="n">RING_API_PARACOUNT</span> <span class="o">==</span> <span class="mi">1</span> <span class="p">)</span> <span class="p">{</span>
        <span class="cm">/* code */</span>
<span class="p">}</span>
</pre></div>
</div>
</div>
<div class="section" id="display-error-message">
<span id="index-5"></span><h2>Display Error Message<a class="headerlink" href="#display-error-message" title="Permalink to this headline">¶</a></h2>
<p>We can display error messages using the RING_API_ERROR() function.</p>
<p>The function will display the error and end the execution of the program.</p>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p class="last">the behaviour of this function can be changed by the Ring code
using Try/Catch/Done statements, so in your C code, use Return after this function.</p>
</div>
<p>Syntax:</p>
<div class="highlight-C"><div class="highlight"><pre><span class="n">RING_API_ERROR</span><span class="p">(</span><span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="n">cErrorMsg</span><span class="p">);</span>
</pre></div>
</div>
<p>The Ring API comes with some of predefined error messages that we can use</p>
<div class="highlight-C"><div class="highlight"><pre><span class="cp">#define RING_API_MISS1PARA &quot;Bad parameters count, the function expect one parameter&quot;</span>
<span class="cp">#define RING_API_MISS2PARA &quot;Bad parameters count, the function expect two parameters&quot;</span>
<span class="cp">#define RING_API_MISS3PARA &quot;Bad parameters count, the function expect three parameters&quot;</span>
<span class="cp">#define RING_API_MISS4PARA &quot;Bad parameters count, the function expect four parameters&quot;</span>
<span class="cp">#define RING_API_BADPARATYPE    &quot;Bad parameter type!&quot;</span>
<span class="cp">#define RING_API_BADPARACOUNT   &quot;Bad parameters count!&quot;</span>
<span class="cp">#define RING_API_BADPARARANGE   &quot;Bad parameters value, error in range!&quot;</span>
<span class="cp">#define RING_API_NOTPOINTER     &quot;Error in parameter, not pointer!&quot;</span>
<span class="cp">#define RING_API_NULLPOINTER    &quot;Error in parameter, NULL pointer!&quot;</span>
<span class="cp">#define RING_API_EMPTYLIST      &quot;Bad parameter, empty list!&quot;</span>
</pre></div>
</div>
</div>
<div class="section" id="check-parameters-type">
<span id="index-6"></span><h2>Check Parameters Type<a class="headerlink" href="#check-parameters-type" title="Permalink to this headline">¶</a></h2>
<p>We can check the parameter type using the next functions</p>
<div class="highlight-C"><div class="highlight"><pre><span class="kt">int</span> <span class="nf">RING_API_ISNUMBER</span><span class="p">(</span><span class="kt">int</span> <span class="n">nParameterNumber</span><span class="p">);</span>
<span class="kt">int</span> <span class="nf">RING_API_ISSTRING</span><span class="p">(</span><span class="kt">int</span> <span class="n">nParameterNumber</span><span class="p">);</span>
<span class="kt">int</span> <span class="nf">RING_API_ISLIST</span><span class="p">(</span><span class="kt">int</span> <span class="n">nParameterNumber</span><span class="p">);</span>
<span class="kt">int</span> <span class="nf">RING_API_ISPOINTER</span><span class="p">(</span><span class="kt">int</span> <span class="n">nParameterNumber</span><span class="p">);</span>
</pre></div>
</div>
<p>The output of these functions will be 1 (True) or 0 (False).</p>
</div>
<div class="section" id="get-parameters-values">
<span id="index-7"></span><h2>Get Parameters Values<a class="headerlink" href="#get-parameters-values" title="Permalink to this headline">¶</a></h2>
<p>We can get paramters values using the next functions</p>
<div class="highlight-C"><div class="highlight"><pre><span class="kt">double</span> <span class="nf">RING_API_GETNUMBER</span><span class="p">(</span><span class="kt">int</span> <span class="n">nParameterNumber</span><span class="p">);</span>
<span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="nf">RING_API_GETSTRING</span><span class="p">(</span><span class="kt">int</span> <span class="n">nParameterNumber</span><span class="p">);</span>
<span class="kt">int</span> <span class="nf">RING_API_GETSTRINGSIZE</span><span class="p">(</span><span class="kt">int</span> <span class="n">nParameterNumber</span><span class="p">);</span>
<span class="n">List</span> <span class="o">*</span><span class="nf">RING_API_GETLIST</span><span class="p">(</span><span class="kt">int</span> <span class="n">nParameterNumber</span><span class="p">);</span>
<span class="kt">void</span> <span class="o">*</span><span class="nf">RING_API_GETCPOINTER</span><span class="p">(</span><span class="kt">int</span> <span class="n">nParameterNumber</span><span class="p">,</span> <span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="n">cPoinerType</span><span class="p">);</span>
<span class="kt">int</span> <span class="nf">RING_API_GETPOINTERTYPE</span><span class="p">(</span><span class="kt">int</span> <span class="n">nParameterNumber</span><span class="p">);</span>
</pre></div>
</div>
</div>
<div class="section" id="return-value">
<span id="index-8"></span><h2>Return Value<a class="headerlink" href="#return-value" title="Permalink to this headline">¶</a></h2>
<p>We can return values from our function using the next functions.</p>
<div class="highlight-C"><div class="highlight"><pre><span class="n">RING_API_RETNUMBER</span><span class="p">(</span><span class="kt">double</span> <span class="n">nValue</span><span class="p">);</span>
<span class="n">RING_API_RETSTRING</span><span class="p">(</span><span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="n">cString</span><span class="p">);</span>
<span class="n">RING_API_RETSTRING2</span><span class="p">(</span><span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="n">cString</span><span class="p">,</span><span class="kt">int</span> <span class="n">nStringSize</span><span class="p">);</span>
<span class="n">RING_API_RETLIST</span><span class="p">(</span><span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">);</span>
<span class="n">RING_API_RETCPOINTER</span><span class="p">(</span><span class="kt">void</span> <span class="o">*</span><span class="n">pValue</span><span class="p">,</span><span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="n">cPointerType</span><span class="p">);</span>
</pre></div>
</div>
</div>
<div class="section" id="function-prototype">
<span id="index-9"></span><h2>Function Prototype<a class="headerlink" href="#function-prototype" title="Permalink to this headline">¶</a></h2>
<p>When we define new function to be used for RingVM extension, we use the next prototype</p>
<div class="highlight-C"><div class="highlight"><pre><span class="kt">void</span> <span class="nf">my_function_name</span><span class="p">(</span> <span class="kt">void</span> <span class="o">*</span><span class="n">pPointer</span> <span class="p">);</span>
</pre></div>
</div>
<p>or we can use the RING_FUNC() Macro</p>
<div class="highlight-C"><div class="highlight"><pre><span class="n">RING_FUNC</span><span class="p">(</span><span class="n">my_function_name</span><span class="p">);</span>
</pre></div>
</div>
</div>
<div class="section" id="sin-function-implementation">
<span id="index-10"></span><h2>Sin() Function Implementation<a class="headerlink" href="#sin-function-implementation" title="Permalink to this headline">¶</a></h2>
<p>The next code represents the sin() function implementation using the Ring API and
the sin() C function.</p>
<div class="highlight-C"><div class="highlight"><pre><span class="kt">void</span> <span class="nf">ring_vm_math_sin</span> <span class="p">(</span> <span class="kt">void</span> <span class="o">*</span><span class="n">pPointer</span> <span class="p">)</span>
<span class="p">{</span>
        <span class="k">if</span> <span class="p">(</span> <span class="n">RING_API_PARACOUNT</span> <span class="o">!=</span> <span class="mi">1</span> <span class="p">)</span> <span class="p">{</span>
                <span class="n">RING_API_ERROR</span><span class="p">(</span><span class="n">RING_API_MISS1PARA</span><span class="p">);</span>
                <span class="k">return</span> <span class="p">;</span>
        <span class="p">}</span>
        <span class="k">if</span> <span class="p">(</span> <span class="n">RING_API_ISNUMBER</span><span class="p">(</span><span class="mi">1</span><span class="p">)</span> <span class="p">)</span> <span class="p">{</span>
                <span class="n">RING_API_RETNUMBER</span><span class="p">(</span><span class="n">sin</span><span class="p">(</span><span class="n">RING_API_GETNUMBER</span><span class="p">(</span><span class="mi">1</span><span class="p">)));</span>
        <span class="p">}</span> <span class="k">else</span> <span class="p">{</span>
                <span class="n">RING_API_ERROR</span><span class="p">(</span><span class="n">RING_API_BADPARATYPE</span><span class="p">);</span>
        <span class="p">}</span>
<span class="p">}</span>
</pre></div>
</div>
</div>
<div class="section" id="fopen-and-fclose-functions-implementation">
<span id="index-11"></span><h2>Fopen() and Fclose() Functions Implementation<a class="headerlink" href="#fopen-and-fclose-functions-implementation" title="Permalink to this headline">¶</a></h2>
<p>The next code represents the fopen() function implementation
using the Ring API and the fopen() C Function.</p>
<p>The function takes two parameters, the first parameter is the file name as string.
The second parameter is the mode as string.</p>
<p>In the file ring_vmfile.h we have some constants to use as the pointer type like</p>
<div class="highlight-C"><div class="highlight"><pre><span class="cp">#define RING_VM_POINTER_FILE    &quot;file&quot;</span>
<span class="cp">#define RING_VM_POINTER_FILEPOS &quot;filepos&quot;</span>
</pre></div>
</div>
<p>The function implementation in ring_vmfile.c</p>
<div class="highlight-C"><div class="highlight"><pre><span class="kt">void</span> <span class="nf">ring_vm_file_fopen</span> <span class="p">(</span> <span class="kt">void</span> <span class="o">*</span><span class="n">pPointer</span> <span class="p">)</span>
<span class="p">{</span>
        <span class="kt">FILE</span> <span class="o">*</span><span class="n">fp</span>  <span class="p">;</span>
        <span class="k">if</span> <span class="p">(</span> <span class="n">RING_API_PARACOUNT</span> <span class="o">!=</span> <span class="mi">2</span> <span class="p">)</span> <span class="p">{</span>
                <span class="n">RING_API_ERROR</span><span class="p">(</span><span class="n">RING_API_MISS2PARA</span><span class="p">);</span>
                <span class="k">return</span> <span class="p">;</span>
        <span class="p">}</span>
        <span class="k">if</span> <span class="p">(</span> <span class="n">RING_API_ISSTRING</span><span class="p">(</span><span class="mi">1</span><span class="p">)</span> <span class="o">&amp;&amp;</span> <span class="n">RING_API_ISSTRING</span><span class="p">(</span><span class="mi">2</span><span class="p">)</span> <span class="p">)</span> <span class="p">{</span>
                <span class="n">fp</span> <span class="o">=</span> <span class="n">fopen</span><span class="p">(</span><span class="n">RING_API_GETSTRING</span><span class="p">(</span><span class="mi">1</span><span class="p">),</span><span class="n">RING_API_GETSTRING</span><span class="p">(</span><span class="mi">2</span><span class="p">));</span>
                <span class="n">RING_API_RETCPOINTER</span><span class="p">(</span><span class="n">fp</span><span class="p">,</span><span class="n">RING_VM_POINTER_FILE</span><span class="p">);</span>
        <span class="p">}</span> <span class="k">else</span> <span class="p">{</span>
                <span class="n">RING_API_ERROR</span><span class="p">(</span><span class="n">RING_API_BADPARATYPE</span><span class="p">);</span>
        <span class="p">}</span>
<span class="p">}</span>
</pre></div>
</div>
<p>The next code represents the fclose() function implementation</p>
<div class="highlight-C"><div class="highlight"><pre><span class="kt">void</span> <span class="nf">ring_vm_file_fclose</span> <span class="p">(</span> <span class="kt">void</span> <span class="o">*</span><span class="n">pPointer</span> <span class="p">)</span>
<span class="p">{</span>
        <span class="kt">FILE</span> <span class="o">*</span><span class="n">fp</span>  <span class="p">;</span>
        <span class="k">if</span> <span class="p">(</span> <span class="n">RING_API_PARACOUNT</span> <span class="o">!=</span> <span class="mi">1</span> <span class="p">)</span> <span class="p">{</span>
                <span class="n">RING_API_ERROR</span><span class="p">(</span><span class="n">RING_API_MISS1PARA</span><span class="p">);</span>
                <span class="k">return</span> <span class="p">;</span>
        <span class="p">}</span>
        <span class="k">if</span> <span class="p">(</span> <span class="n">RING_API_ISPOINTER</span><span class="p">(</span><span class="mi">1</span><span class="p">)</span> <span class="p">)</span> <span class="p">{</span>
                <span class="n">fp</span> <span class="o">=</span> <span class="p">(</span><span class="kt">FILE</span> <span class="o">*</span><span class="p">)</span> <span class="n">RING_API_GETCPOINTER</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span><span class="n">RING_VM_POINTER_FILE</span><span class="p">)</span> <span class="p">;</span>
                <span class="k">if</span> <span class="p">(</span> <span class="n">fp</span> <span class="o">!=</span> <span class="nb">NULL</span> <span class="p">)</span> <span class="p">{</span>
                        <span class="n">RING_API_RETNUMBER</span><span class="p">(</span><span class="n">fclose</span><span class="p">(</span><span class="n">fp</span><span class="p">));</span>
                        <span class="n">RING_API_SETNULLPOINTER</span><span class="p">(</span><span class="mi">1</span><span class="p">);</span>
                <span class="p">}</span>
        <span class="p">}</span> <span class="k">else</span> <span class="p">{</span>
                <span class="n">RING_API_ERROR</span><span class="p">(</span><span class="n">RING_API_BADPARATYPE</span><span class="p">);</span>
        <span class="p">}</span>
<span class="p">}</span>
</pre></div>
</div>
<p>From fopen() and fclose() implementation we learned</p>
<p>1 - how to return C pointer using RING_API_RETCPOINTER() function</p>
<p>2 - how to check if the parameter is a pointer using the RING_API_ISPOINTER() function</p>
<p>3 - how to get C pointer value using the RING_API_GETCPOINTER() function</p>
<p>4 - how to set the C pointer variable (in RingVM) to NULL using the RING_API_SETNULLPOINTER() function</p>
</div>
<div class="section" id="ring-api-list-functions">
<span id="index-12"></span><h2>Ring API - List Functions<a class="headerlink" href="#ring-api-list-functions" title="Permalink to this headline">¶</a></h2>
<p>In this section we will learn about the list functions provided by the Ring API to create new lists and
manipulate the list items.</p>
<div class="highlight-C"><div class="highlight"><pre><span class="n">List</span> <span class="o">*</span> <span class="nf">ring_list_new</span> <span class="p">(</span> <span class="kt">int</span> <span class="n">nSize</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_list_newitem</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span> <span class="p">)</span> <span class="p">;</span>
<span class="n">Item</span> <span class="o">*</span> <span class="nf">ring_list_getitem</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span><span class="kt">int</span> <span class="n">index</span> <span class="p">)</span> <span class="p">;</span>
<span class="n">List</span> <span class="o">*</span> <span class="nf">ring_list_delete</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_list_deleteitem</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span><span class="kt">int</span> <span class="n">index</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_list_print</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">int</span> <span class="nf">ring_list_gettype</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span> <span class="kt">int</span> <span class="n">index</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_list_setint</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span> <span class="kt">int</span> <span class="n">index</span> <span class="p">,</span><span class="kt">int</span> <span class="n">number</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_list_addint</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span><span class="kt">int</span> <span class="n">x</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_list_setpointer</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span> <span class="kt">int</span> <span class="n">index</span> <span class="p">,</span><span class="kt">void</span> <span class="o">*</span><span class="n">pValue</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_list_addpointer</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span><span class="kt">void</span> <span class="o">*</span><span class="n">pValue</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_list_setfuncpointer</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span> <span class="kt">int</span> <span class="n">index</span> <span class="p">,</span><span class="kt">void</span> <span class="p">(</span><span class="o">*</span><span class="n">pFunc</span><span class="p">)(</span><span class="kt">void</span> <span class="o">*</span><span class="p">)</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_list_addfuncpointer</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span><span class="kt">void</span> <span class="p">(</span><span class="o">*</span><span class="n">pFunc</span><span class="p">)(</span><span class="kt">void</span> <span class="o">*</span><span class="p">)</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">int</span> <span class="nf">ring_list_isfuncpointer</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span> <span class="kt">int</span> <span class="n">index</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_list_setdouble</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span> <span class="kt">int</span> <span class="n">index</span> <span class="p">,</span><span class="kt">double</span> <span class="n">number</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_list_adddouble</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span><span class="kt">double</span> <span class="n">x</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_list_setstring</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span> <span class="kt">int</span> <span class="n">index</span> <span class="p">,</span><span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="n">str</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_list_setstring2</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span> <span class="kt">int</span> <span class="n">index</span> <span class="p">,</span><span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="n">str</span><span class="p">,</span><span class="kt">int</span> <span class="n">nStrSize</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_list_addstring</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span><span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="n">str</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_list_addstring2</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span><span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="n">str</span><span class="p">,</span><span class="kt">int</span> <span class="n">nStrSize</span> <span class="p">)</span> <span class="p">;</span>
<span class="n">List</span> <span class="o">*</span> <span class="nf">ring_list_newlist</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span> <span class="p">)</span> <span class="p">;</span>
<span class="n">List</span> <span class="o">*</span> <span class="nf">ring_list_getlist</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span> <span class="kt">int</span> <span class="n">index</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_list_setlist</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span> <span class="kt">int</span> <span class="n">index</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_list_setactiveitem</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span> <span class="n">Items</span> <span class="o">*</span><span class="n">pItems</span><span class="p">,</span> <span class="kt">int</span> <span class="n">index</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_list_copy</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pNewList</span><span class="p">,</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">int</span> <span class="nf">ring_list_isnumber</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span> <span class="kt">int</span> <span class="n">index</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">int</span> <span class="nf">ring_list_isstring</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span> <span class="kt">int</span> <span class="n">index</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">int</span> <span class="nf">ring_list_islist</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span> <span class="kt">int</span> <span class="n">index</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">int</span> <span class="nf">ring_list_ispointer</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span> <span class="kt">int</span> <span class="n">index</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_list_deleteallitems</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_list_insertitem</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span><span class="kt">int</span> <span class="n">x</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_list_insertint</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span><span class="kt">int</span> <span class="n">nPos</span><span class="p">,</span><span class="kt">int</span> <span class="n">x</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_list_insertdouble</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span><span class="kt">int</span> <span class="n">nPos</span><span class="p">,</span><span class="kt">double</span> <span class="n">x</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_list_insertpointer</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span><span class="kt">int</span> <span class="n">nPos</span><span class="p">,</span><span class="kt">void</span> <span class="o">*</span><span class="n">pValue</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_list_insertstring</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span><span class="kt">int</span> <span class="n">nPos</span><span class="p">,</span><span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="n">str</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_list_insertstring2</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span><span class="kt">int</span> <span class="n">nPos</span><span class="p">,</span><span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="n">str</span><span class="p">,</span><span class="kt">int</span> <span class="n">nStrSize</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_list_insertfuncpointer</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span><span class="kt">int</span> <span class="n">nPos</span><span class="p">,</span><span class="kt">void</span> <span class="p">(</span><span class="o">*</span><span class="n">pFunc</span><span class="p">)(</span><span class="kt">void</span> <span class="o">*</span><span class="p">)</span> <span class="p">)</span> <span class="p">;</span>
<span class="n">List</span> <span class="o">*</span> <span class="nf">ring_list_insertlist</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span><span class="kt">int</span> <span class="n">nPos</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">int</span> <span class="nf">ring_list_isiteminsidelist</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span><span class="n">Item</span> <span class="o">*</span><span class="n">pItem</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">int</span> <span class="nf">ring_list_findstring</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span><span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="n">str</span><span class="p">,</span><span class="kt">int</span> <span class="n">nColumn</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">int</span> <span class="nf">ring_list_finddouble</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span><span class="kt">double</span> <span class="n">nNum1</span><span class="p">,</span><span class="kt">int</span> <span class="n">nColumn</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_list_sortnum</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span><span class="kt">int</span> <span class="n">left</span><span class="p">,</span><span class="kt">int</span> <span class="n">right</span><span class="p">,</span><span class="kt">int</span> <span class="n">nColumn</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_list_sortstr</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span><span class="kt">int</span> <span class="n">left</span><span class="p">,</span><span class="kt">int</span> <span class="n">right</span><span class="p">,</span><span class="kt">int</span> <span class="n">nColumn</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">int</span> <span class="nf">ring_list_binarysearchnum</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span><span class="kt">double</span> <span class="n">nNum1</span><span class="p">,</span><span class="kt">int</span> <span class="n">nColumn</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">int</span> <span class="nf">ring_list_binarysearchstr</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span><span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="n">cFind</span><span class="p">,</span><span class="kt">int</span> <span class="n">nColumn</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_list_swap</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span><span class="kt">int</span> <span class="n">x</span><span class="p">,</span><span class="kt">int</span> <span class="n">y</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">double</span> <span class="nf">ring_list_getdoublecolumn</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span><span class="kt">int</span> <span class="n">nIndex</span><span class="p">,</span><span class="kt">int</span> <span class="n">nColumn</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">char</span> <span class="o">*</span> <span class="nf">ring_list_getstringcolumn</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span><span class="kt">int</span> <span class="n">nIndex</span><span class="p">,</span><span class="kt">int</span> <span class="n">nColumn</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_list_genarray</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_list_deletearray</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_list_genhashtable</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_list_genhashtable2</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_list_refcopy</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pNewList</span><span class="p">,</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_list_clear</span> <span class="p">(</span> <span class="n">List</span> <span class="o">*</span><span class="n">pList</span> <span class="p">)</span> <span class="p">;</span>
<span class="cm">/* Macro */</span>
<span class="n">ring_list_isdouble</span><span class="p">(</span><span class="n">pList</span><span class="p">,</span><span class="n">index</span><span class="p">)</span>
<span class="n">ring_list_isint</span><span class="p">(</span><span class="n">pList</span><span class="p">,</span><span class="n">index</span><span class="p">)</span>
<span class="n">ring_list_deletelastitem</span><span class="p">(</span><span class="n">x</span><span class="p">)</span>
<span class="n">ring_list_gethashtable</span><span class="p">(</span><span class="n">x</span><span class="p">)</span>
<span class="n">ring_list_getint</span><span class="p">(</span><span class="n">pList</span><span class="p">,</span><span class="n">index</span><span class="p">)</span>
<span class="n">ring_list_getpointer</span><span class="p">(</span><span class="n">pList</span><span class="p">,</span><span class="n">index</span><span class="p">)</span>
<span class="n">ring_list_getfuncpointer</span><span class="p">(</span><span class="n">pList</span><span class="p">,</span><span class="n">index</span><span class="p">)</span>
<span class="n">ring_list_callfuncpointer</span><span class="p">(</span><span class="n">pList</span><span class="p">,</span><span class="n">index</span><span class="p">,</span><span class="n">x</span><span class="p">)</span>
<span class="n">ring_list_getdouble</span><span class="p">(</span><span class="n">pList</span><span class="p">,</span><span class="n">index</span><span class="p">)</span>
<span class="n">ring_list_getstring</span><span class="p">(</span><span class="n">pList</span><span class="p">,</span><span class="n">index</span><span class="p">)</span>
<span class="n">ring_list_getstringobject</span><span class="p">(</span><span class="n">pList</span><span class="p">,</span><span class="n">index</span><span class="p">)</span>
<span class="n">ring_list_getstringsize</span><span class="p">(</span><span class="n">pList</span><span class="p">,</span><span class="n">index</span><span class="p">)</span>
<span class="n">ring_list_getsize</span><span class="p">(</span><span class="n">x</span><span class="p">)</span> <span class="p">(</span><span class="n">x</span><span class="o">-&gt;</span><span class="n">nSize</span><span class="p">)</span>
</pre></div>
</div>
</div>
<div class="section" id="ring-api-string-functions">
<span id="index-13"></span><h2>Ring API - String Functions<a class="headerlink" href="#ring-api-string-functions" title="Permalink to this headline">¶</a></h2>
<p>In this section we will learn about the string functions provided by the Ring API to create new string and
manipulate the string content.</p>
<div class="highlight-C"><div class="highlight"><pre><span class="n">String</span> <span class="o">*</span> <span class="nf">ring_string_new</span> <span class="p">(</span> <span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="n">str</span> <span class="p">)</span> <span class="p">;</span>
<span class="n">String</span> <span class="o">*</span> <span class="nf">ring_string_new2</span> <span class="p">(</span> <span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="n">str</span><span class="p">,</span><span class="kt">int</span> <span class="n">nStrSize</span> <span class="p">)</span> <span class="p">;</span>
<span class="n">String</span> <span class="o">*</span> <span class="nf">ring_string_delete</span> <span class="p">(</span> <span class="n">String</span> <span class="o">*</span><span class="n">pString</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">int</span> <span class="nf">ring_string_size</span> <span class="p">(</span> <span class="n">String</span> <span class="o">*</span><span class="n">pString</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_string_set</span> <span class="p">(</span> <span class="n">String</span> <span class="o">*</span><span class="n">pString</span><span class="p">,</span><span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="n">str</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_string_set2</span> <span class="p">(</span> <span class="n">String</span> <span class="o">*</span><span class="n">pString</span><span class="p">,</span><span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="n">str</span><span class="p">,</span><span class="kt">int</span> <span class="n">nStrSize</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_string_add</span> <span class="p">(</span> <span class="n">String</span> <span class="o">*</span><span class="n">pString</span><span class="p">,</span><span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="n">str</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_string_add2</span> <span class="p">(</span> <span class="n">String</span> <span class="o">*</span><span class="n">pString</span><span class="p">,</span><span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="n">str</span><span class="p">,</span><span class="kt">int</span> <span class="n">nStrSize</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_string_print</span> <span class="p">(</span> <span class="n">String</span> <span class="o">*</span><span class="n">pString</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">void</span> <span class="nf">ring_string_setfromint</span> <span class="p">(</span> <span class="n">String</span> <span class="o">*</span><span class="n">pString</span><span class="p">,</span><span class="kt">int</span> <span class="n">x</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">char</span> <span class="o">*</span> <span class="nf">ring_string_lower</span> <span class="p">(</span> <span class="kt">char</span> <span class="o">*</span><span class="n">cStr</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">char</span> <span class="o">*</span> <span class="nf">ring_string_upper</span> <span class="p">(</span> <span class="kt">char</span> <span class="o">*</span><span class="n">cStr</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">char</span> <span class="o">*</span> <span class="nf">ring_string_lower2</span> <span class="p">(</span> <span class="kt">char</span> <span class="o">*</span><span class="n">cStr</span><span class="p">,</span><span class="kt">int</span> <span class="n">nStrSize</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">char</span> <span class="o">*</span> <span class="nf">ring_string_upper2</span> <span class="p">(</span> <span class="kt">char</span> <span class="o">*</span><span class="n">cStr</span><span class="p">,</span><span class="kt">int</span> <span class="n">nStrSize</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">char</span> <span class="o">*</span> <span class="nf">ring_string_find</span> <span class="p">(</span> <span class="kt">char</span> <span class="o">*</span><span class="n">cStr1</span><span class="p">,</span><span class="kt">char</span> <span class="o">*</span><span class="n">cStr2</span> <span class="p">)</span> <span class="p">;</span>
<span class="kt">char</span> <span class="o">*</span> <span class="nf">ring_string_find2</span> <span class="p">(</span> <span class="kt">char</span> <span class="o">*</span><span class="n">cStr1</span><span class="p">,</span><span class="kt">int</span> <span class="n">nStrSize1</span><span class="p">,</span><span class="kt">char</span> <span class="o">*</span><span class="n">cStr2</span><span class="p">,</span><span class="kt">int</span> <span class="n">nStrSize2</span> <span class="p">)</span> <span class="p">;</span>
<span class="cm">/* Macro */</span>
<span class="n">ring_string_tolower</span><span class="p">(</span><span class="n">x</span><span class="p">)</span>
<span class="n">ring_string_toupper</span><span class="p">(</span><span class="n">x</span><span class="p">)</span>
<span class="n">ring_string_get</span><span class="p">(</span><span class="n">x</span><span class="p">)</span>
</pre></div>
</div>
</div>
<div class="section" id="mysql-columns-function-implementation">
<span id="index-14"></span><h2>MySQL_Columns() Function Implementation<a class="headerlink" href="#mysql-columns-function-implementation" title="Permalink to this headline">¶</a></h2>
<p>The next code presents the MySQL_Columns() function implementation.</p>
<p>This function returns table columns information.</p>
<div class="highlight-C"><div class="highlight"><pre><span class="kt">void</span> <span class="nf">ring_vm_mysql_columns</span> <span class="p">(</span> <span class="kt">void</span> <span class="o">*</span><span class="n">pPointer</span> <span class="p">)</span>
<span class="p">{</span>
        <span class="n">MYSQL</span> <span class="o">*</span><span class="n">con</span>  <span class="p">;</span>
        <span class="n">MYSQL_RES</span> <span class="o">*</span><span class="n">result</span>  <span class="p">;</span>
        <span class="kt">int</span> <span class="n">nColumns</span><span class="p">,</span><span class="n">x</span>  <span class="p">;</span>
        <span class="n">MYSQL_ROW</span> <span class="n">row</span>  <span class="p">;</span>
        <span class="n">MYSQL_FIELD</span> <span class="o">*</span><span class="n">field</span>  <span class="p">;</span>
        <span class="n">List</span> <span class="o">*</span><span class="n">pList</span><span class="p">,</span> <span class="o">*</span><span class="n">pList2</span>  <span class="p">;</span>
        <span class="k">if</span> <span class="p">(</span> <span class="n">RING_API_PARACOUNT</span> <span class="o">!=</span> <span class="mi">1</span> <span class="p">)</span> <span class="p">{</span>
                <span class="n">RING_API_ERROR</span><span class="p">(</span><span class="n">RING_API_MISS1PARA</span><span class="p">);</span>
                <span class="k">return</span> <span class="p">;</span>
        <span class="p">}</span>
        <span class="k">if</span> <span class="p">(</span> <span class="n">RING_API_ISPOINTER</span><span class="p">(</span><span class="mi">1</span><span class="p">)</span> <span class="p">)</span> <span class="p">{</span>
                <span class="n">con</span> <span class="o">=</span> <span class="p">(</span><span class="n">MYSQL</span> <span class="o">*</span><span class="p">)</span> <span class="n">RING_API_GETCPOINTER</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span><span class="n">RING_VM_POINTER_MYSQL</span><span class="p">)</span> <span class="p">;</span>
                <span class="k">if</span> <span class="p">(</span> <span class="n">con</span> <span class="o">==</span> <span class="nb">NULL</span> <span class="p">)</span> <span class="p">{</span>
                        <span class="k">return</span> <span class="p">;</span>
                <span class="p">}</span>
                <span class="n">result</span> <span class="o">=</span> <span class="n">mysql_store_result</span><span class="p">(</span><span class="n">con</span><span class="p">);</span>
                <span class="k">if</span> <span class="p">(</span> <span class="n">result</span> <span class="o">==</span> <span class="nb">NULL</span> <span class="p">)</span> <span class="p">{</span>
                        <span class="n">RING_API_RETNUMBER</span><span class="p">(</span><span class="mi">0</span><span class="p">);</span>
                        <span class="k">return</span> <span class="p">;</span>
                <span class="p">}</span>
                <span class="n">pList</span> <span class="o">=</span> <span class="n">RING_API_NEWLIST</span> <span class="p">;</span>
                <span class="n">nColumns</span> <span class="o">=</span> <span class="n">mysql_num_fields</span><span class="p">(</span><span class="n">result</span><span class="p">);</span>
                <span class="k">if</span> <span class="p">(</span> <span class="n">row</span> <span class="o">=</span> <span class="n">mysql_fetch_row</span><span class="p">(</span><span class="n">result</span><span class="p">)</span> <span class="p">)</span> <span class="p">{</span>
                        <span class="k">while</span> <span class="p">(</span> <span class="n">field</span> <span class="o">=</span> <span class="n">mysql_fetch_field</span><span class="p">(</span><span class="n">result</span><span class="p">)</span> <span class="p">)</span> <span class="p">{</span>
                                <span class="n">pList2</span> <span class="o">=</span> <span class="n">ring_list_newlist</span><span class="p">(</span><span class="n">pList</span><span class="p">);</span>
                                <span class="n">ring_list_addstring</span><span class="p">(</span><span class="n">pList2</span><span class="p">,</span><span class="n">field</span><span class="o">-&gt;</span><span class="n">name</span><span class="p">);</span>
                                <span class="n">ring_list_adddouble</span><span class="p">(</span><span class="n">pList2</span><span class="p">,</span><span class="n">field</span><span class="o">-&gt;</span><span class="n">length</span><span class="p">);</span>
                                <span class="n">ring_list_adddouble</span><span class="p">(</span><span class="n">pList2</span><span class="p">,</span><span class="n">field</span><span class="o">-&gt;</span><span class="n">type</span><span class="p">);</span>
                                <span class="n">ring_list_adddouble</span><span class="p">(</span><span class="n">pList2</span><span class="p">,</span><span class="n">field</span><span class="o">-&gt;</span><span class="n">flags</span><span class="p">);</span>
                        <span class="p">}</span>
                <span class="p">}</span>
                <span class="n">mysql_free_result</span><span class="p">(</span><span class="n">result</span><span class="p">);</span>
                <span class="n">RING_API_RETLIST</span><span class="p">(</span><span class="n">pList</span><span class="p">);</span>
        <span class="p">}</span> <span class="k">else</span> <span class="p">{</span>
                <span class="n">RING_API_ERROR</span><span class="p">(</span><span class="n">RING_API_BADPARATYPE</span><span class="p">);</span>
        <span class="p">}</span>
<span class="p">}</span>
</pre></div>
</div>
<p>Lists are of type List, in the previoud function we declared two pointers of type List
using List <a href="#id1"><span class="problematic" id="id2">*</span></a>pList, <a href="#id3"><span class="problematic" id="id4">*</span></a>pList2;</p>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p class="last">The function uses RING_API_NEWLIST to create new list instead of ring_list_new()
to create the list in Temp. Memory related to the function scope. This way we can
return the list from the function. Also we don&#8217;t delete the list, if it&#8217;s stored in
a variable by Ring Code it will be saved, if not it will be automatically deleted by RingVM.</p>
</div>
<p>The list can contains sub lists, we used the function ring_list_newlist() to create a sublist.</p>
<p>The function ring_list_addstring() is used to add string items to the list/sublist.</p>
<p>The function ring_list_adddouble() is used to add numeric items to the list/sublist.</p>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p class="last">All numeric items in lists returned from RingVM extension functions must be of type double
and added to the list using ring_list_adddouble() function.</p>
</div>
<p>We return the list from the extension function using the RING_API_RETLIST() function.</p>
</div>
<div class="section" id="dynamic-shared-libraries-dll-so-and-loadlib-function">
<span id="index-15"></span><h2>Dynamic/Shared Libraries (DLL/So) and LoadLib() function<a class="headerlink" href="#dynamic-shared-libraries-dll-so-and-loadlib-function" title="Permalink to this headline">¶</a></h2>
<p>Instead of rebuilding the RingVM after writing new functions using C/C++ and the Ring API, we can create
a DLL/So file and dynamically use the functions provided by this file in the runtime using the LoadLib() function.</p>
<p>Dynamic library example in C</p>
<div class="highlight-C"><div class="highlight"><pre><span class="cp">#include &quot;ring.h&quot;</span>

<span class="n">RING_DLL</span> <span class="nf">__declspec</span><span class="p">(</span><span class="n">dllexport</span><span class="p">)</span>

<span class="n">RING_FUNC</span><span class="p">(</span><span class="n">ring_ringlib_dlfunc</span><span class="p">)</span>
<span class="p">{</span>
        <span class="n">printf</span><span class="p">(</span><span class="s">&quot;Message from dlfunc&quot;</span><span class="p">);</span>
<span class="p">}</span>

<span class="n">RING_DLL</span> <span class="kt">void</span> <span class="nf">ringlib_init</span><span class="p">(</span><span class="n">RingState</span> <span class="o">*</span><span class="n">pRingState</span><span class="p">)</span>
<span class="p">{</span>
        <span class="n">ring_vm_funcregister</span><span class="p">(</span><span class="s">&quot;dlfunc&quot;</span><span class="p">,</span><span class="n">ring_ringlib_dlfunc</span><span class="p">);</span>
<span class="p">}</span>
</pre></div>
</div>
<p>the idea is to create the ringlib_init() function, this function will be called by the RingVM when we use the generated DLL
file though the LoadLib() function.</p>
<p>Inside the ringlib_init() function we can register the module function or call a function that do the registration process
for all of the module functions.</p>
<p>The next Ring code demonstrates how to use the DLL library during the runtime.</p>
<div class="highlight-none"><div class="highlight"><pre>See &quot;Dynamic DLL&quot; + NL
LoadLib(&quot;ringlib.dll&quot;)
dlfunc()
</pre></div>
</div>
<p>Output:</p>
<div class="highlight-none"><div class="highlight"><pre>Dynamic DLL
Message from dlfunc
</pre></div>
</div>
</div>
</div>


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<li><a class="reference internal" href="#">Extension using the C/C++ languages</a><ul>
<li><a class="reference internal" href="#ring-ext-h">ring_ext.h</a></li>
<li><a class="reference internal" href="#ring-ext-c">ring_ext.c</a></li>
<li><a class="reference internal" href="#module-organization">Module Organization</a></li>
<li><a class="reference internal" href="#function-structure">Function Structure</a></li>
<li><a class="reference internal" href="#check-parameters-count">Check Parameters Count</a></li>
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<li><a class="reference internal" href="#sin-function-implementation">Sin() Function Implementation</a></li>
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<li><a class="reference internal" href="#ring-api-list-functions">Ring API - List Functions</a></li>
<li><a class="reference internal" href="#ring-api-string-functions">Ring API - String Functions</a></li>
<li><a class="reference internal" href="#mysql-columns-function-implementation">MySQL_Columns() Function Implementation</a></li>
<li><a class="reference internal" href="#dynamic-shared-libraries-dll-so-and-loadlib-function">Dynamic/Shared Libraries (DLL/So) and LoadLib() function</a></li>
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