Question

Why does is_int always return false in the following situation?

echo $_GET['id']; //3
if(is_int($_GET['id']))
    echo 'int'; //not executed

Answer 1

Why does is_int always return false?

Because $_GET["id"] is a string, even if it happens to contain a number.

Your options:

• Use the filter extension. filter_input(INPUT_GET, "id", FILTER_VALIDATE_INT) will return an integer typed variable if the variable exists, is not an array, represents an integer and that integer is within the valid bounds. Otherwise it will return false.

• Force cast it to integer (int)$_GET["id"] – probably not what you want because you can’t properly handle errors (i.e. “id” not being a number)

• Use ctype_digit() to make sure the string consists only of numbers, and therefore is an integer – technically, this returns true also with very large numbers that are beyond int‘s scope, but I doubt this will be a problem. However, note that this method will not recognize negative numbers.

Do not use:

• is_numeric() because it will also recognize float values (1.23132)