is_int and GET or POST

Checking for integers using is_int($value) will return false for strings.

Casting the value -- is_int((int) $value) -- won't help because strings and floats will result in false positive.

is_numeric($value) will reject non numeric strings, but floats still pass.

But the thing is, a float cast to integer won't equal itself if it's not an integer. So I came up with something like this:

$isInt = (is_numeric($value) && (int) $value == $value);

It works fine for integers and strings ... and some floating numbers.

But unfortunately, this will not work for some float integers.

$number = pow(125, 1/3); // float(5) -- cube root of 125
var_dump((int) $number == $number); // bool(false)

But that's a whole different question.

Because HTTP variables are always either strings, or arrays. And the elements of arrays are always strings or arrays.

You want the is_numeric function, which will return true for "4". Either that, or cast the variable to an int $foo = (int) $_GET['id']...

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:

How i fixed it:

$int_id = (int) $_GET["id"];

if((string)$int_id == $_GET["id"]) {
echo $_GET["id"];
}

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