Check if variable is a number and positive integer in PHP?

Question

For example, say:

<?php

    // Grab the ID from URL, e.g. example.com/?p=123
    $post_id = $_GET['p'];

?>

How do I check if variable $post_id is a number, and a positive integer at that (i.e. 0-9, not a floating point number, fraction, or a negative number)?

EDIT: Can't use is_int 'cause $_GET returns a string. Think I need to use intval() or ctype_digit(), with the latter seeming more appropriate. For example:

if( ctype_digit( $post_id ) ) { ... }

Answer 1

To check if a string input is a positive integer, i always use the function ctype_digit. This is much easier to understand and faster than a regular expression.

if (isset($_GET['p']) && ctype_digit($_GET['p']))
{
  // the get input contains a positive number and is safe
}

Answer 2

is_int is only for type detection. And request parameters are string by default. So it won't work. http://php.net/is_int

A type independent working solution:

if(preg_match('/^\d+$/D',$post_id) && ($post_id>0)){
   print "Positive integer!";
}

Answer 3

use ctype_digit but, for a positive number, you need to add the "> 0" check

if (isset($_GET['p']) && ctype_digit($_GET['p']) && ($_GET['p'] > 0))
{
  // the get input contains a positive number and is safe
}

in general, use ctype_digit in this way

if (ctype_digit((string)$var))

to prevent errors

Answer 4

You can do it like this:-

if( is_int( $_GET['id'] ) && $_GET['id'] > 0 ) {

   //your stuff here

}

Answer 5

positive integer and greater that 0

if(is_int($post_id) && $post_id > 0) {/* your code here */}

Answer 6

You can use is_numeric to check if a var is a number. You also have is_int. To test if it's positive juste do something like if (var > 0).