check if string is a number

Hello,
I have string.
Is there any function that check if this string is only a numbers?

Thanks,
Roi.

 

http://www.php.net/manual/en/function.ctype-digit.php

if(ctype_digit($string)) {
echo "it's a number";
}

There's also is_numeric, however, I chose ctype functions as they can also test for alpha, upper case, lower case. Check out the page on php.net as there are some limitations.

 

Thanks....