PHP validating integers

Question

Hi,

I was wondering, what would be the best way to validate an integer. I'd like this to work with strings as well, so I could to something like

(string)+00003 -> (int)3 (valid)

(string)-027 -> (int)-27 (valid)

(int)33 -> (int)33 (valid)

(string)'33a' -> (FALSE) (invalid)

That is what i've go so far:

function parseInt($int){
    //If $int already is integer, return it
    if(is_int($int)){return $int;}
//If not, convert it to string
$int=(string)$int;
//If we have '+' or '-' at the beginning of the string, remove them
$validate = ($int[0] === '-' || $int[0] === '+')?substr($int, 1):$int;
//If $validate matches pattern 0-9 convert $int to integer and return it
//otherwise return false
return preg_match('/^[0-9]+$/', $validate)?(int)$int:FALSE;
}

As far as I tested, this function works, but it looks like a clumsy workaround.

Is there any better way to write this kind of function. I've also tried

filter_var($foo, FILTER_VALIDATE_INT);

but it won't accept values like '0003', '-0' etc.

Answer 1

there is a native function called intval(). Is that's what you're looking for?

Answer 2

You could try ctype_digit or is_numeric

Answer 3

it won't accept "0003" cause it's not 'clear' integer. Integer can't start with zero but it can be negative (notice that you remove '-' with your function). As said before me, use ctype_digit or is_numeric

Answer 4

You could use intval as Jacob suggests.

However, if you want a Locale aware int validation class, then I suggest using the Zend Framework's Zend_Validate_Int validator.

Usage

<?php
$v = new Zend_Validate_Int();
if ($v->isValid($myVal)) {
    // yay
} else {
    // fail
}

Note that because of the pick-and-choose structure of the Zend Framework, you don't need to use this for your entire application. The Validators have minimal dependencies on Zend_Locale, for locale aware validation, and Zend_Registry.

Answer 5

Quick and dirty way, won't handle '0003' as far as I know.

function parseInt($in) {
    return ($in == intval($in) ? $in : false);
}

Answer 6

You could also use PEAR's Validate package; http://pear.php.net/manual/en/package.validate.validate.number.php

Various option are:

1. decimal (mixed) - Decimal chars or false when decimal not allowed. For example ",." to allow both "." and ",".
2. dec_prec (int) - Number of allowed decimals.
3. min (float) - Minimum value.
4. max (float) - Maximum value.