Add Prime Number in Julia

archive/j/julia/prime-number.jl

@@ -0,0 +1,31 @@
+function err() 
+    return "Usage: please input a non-negative integer"
+ end
+
+
+function isPrime(num)
+# handle 0 and 1
+    if num <= 1 
+        return "composite"
+    end 
+
+# default handler
+    for i in 2:sqrt(num) #loop starting at 2, ending at the squareroot of the input
+        if (num % i == 0)
+            return "composite"
+        end
+    end
+    return "prime"             
+end
+
+#check for a valid input
+try
+    n = parse(Int, ARGS[1])
+    if n < 0
+        println(err())
+    else
+        println(isPrime(n))
+    end
+catch e
+    println(err())
+end