diff --git a/plugins/include/string.inc b/plugins/include/string.inc
index feacf0df..f9955dd2 100755
--- a/plugins/include/string.inc
+++ b/plugins/include/string.inc
@@ -125,4 +125,17 @@ native strcat(dest[], const source[], maxlength);
 native strfind(const string[], const sub[], ignorecase=0, pos=0);
 
 /* Compares two strings with the C function strcmp().  Returns 0 on equal. */
-native strcmp(const string1[], const string2[], ignorecase=0);
\ No newline at end of file
+native strcmp(const string1[], const string2[], ignorecase=0);
+
+// tests if given string contains only digits
+stock bool:is_str_num(sString[])
+{
+    new i = 0, len = strlen(sString);
+    
+    do
+    {
+        if (!isdigit(sString[i]))
+            return false;
+    } while (i++ < len);
+    return true;
+}
\ No newline at end of file