php validate integer - php

Question

I`m wonder why this not working
echo gettype($_GET['id']); //returns string
if(is_int($_GET['id']))
{
echo 'Integer';
}
How to validate data passing from GET/POST if it is integer ?

Answer 1

Can use
$validatedValue = filter_input(INPUT_GET, 'id', FILTER_VALIDATE_INT);
See http://php.net/filter_input and related functions.

Answer 2

The manual says:
To test if a variable is a number or a
numeric string (such as form input,
which is always a string), you must
use is_numeric().
Alternative you can use the regex based test as:
if(preg_match('/^\d+$/',$_GET['id'])) {
// valid input.
} else {
// invalid input.
}

Answer 3

What about intval?
$int = intval($_GET['id']);

Answer 4

To validate form data (string) as an integer, you should use ctype_digit()
It returns TRUE if every character in the string text is a decimal digit, FALSE otherwise.
(PHP 4 >= 4.0.4, PHP 5)
Reference: http://php.net/manual/en/function.ctype-digit.php

Answer 5

Try:
if(isNumeric($_GET['id'])) {
$cast_int = (int)$_GET['id'];
}
if(isset($cast_int)) {
echo gettype($cast_int)."<br />\n";
if(is_int($cast_int))
{
echo 'Integer'."<br />\n";
}
} else {
echo gettype($_GET['id'])." was passed<br />\n";
}
function isNumeric($numeric) {
return preg_match("/^[0-9]+$/", $numeric);
}

Answer 6

It sounds like you are checking if a string contains an integer, rather than if that variable is an integer. If so, you should check out php's regex (regular expression) functionality. It allows you to check for very specific patterns in a string to validate it for whatever criteria. (such as if it contains only number characters)
Here's the php page
http://php.net/manual/en/function.preg-match.php
and here's a cheat sheet on regular expressions (to make the $pattern string)
http://regexpr.com/cheatsheet/

Answer 7

I take a slightly more paranoid approach to sanitizing GET input
function sanitize_int($integer, $min='', $max='')
{
$int = intval($integer);
if((($min != '') && ($int < $min)) || (($max != '') && ($int > $max)))
return FALSE;
return $int;
}
To be even safer, you can extract only numbers first and then run the function above
function sanitize_paranoid_string($string, $min='', $max='')
{
$string = preg_replace("/[^a-zA-Z0-9]/", "", $string);
$len = strlen($string);
if((($min != '') && ($len < $min)) || (($max != '') && ($len > $max)))
return FALSE;
return $string;
}
Code from: http://libox.net