'210010106140040100' == '210010106140040101'

Posted on 16th Feb 2014 07:03 pm by admin

Debugging this simple line of a PHP script

Code: if($a == $b){ }
I've found that with value of
$a = '210010106140040100' (type = string)
$b = '210010106140040101' (type = string)

the result of the comparison is TRUE

the same if i compare 2 integer

$a = 210010106140040100 (type = int)
$b = 210010106140040101 (type = int)

$a == $b ( true )

If I use the === operator

'210010106140040100' === '210010106140040101' (comparison of strings: result is FALSE)
210010106140040100 === 210010106140040101 (comparison of numbers: result is TRUE)

I think it could be caused by the fact that the string is 'like' integer, but exceed the standard size of integer number.
But the final result remain a mistery for me: I've tested some others 'big' numbers and I've found for example:

18014398509481980==18014398509481981 (true) !!!!
18014398509481982==18014398509481981 (false) !!!!

In my specific script i can handle this specific comparison using the === operator, because i can assume that the variable are string.

But i'd like to know why this happen, and i'd appreciate suggestions about how to efficiently compare 'big' integers.

Thanks!

I use PHP 5.2 with IIS

Your Answer:

Login to answer

Other forums

Unable to retreve the values from Mysql Query
Hi,

Here is the php code that I have, Query is running properly in phpmyadmin and is resu

phph within href not showing php if change ? to &
Code: [Select]<a href="<?php echo $puser; ?>?m=<?php=(($m-1)&l

Add a sign-up feature to a flat file login script
I'm working on a flat file login script and I would like to add a sign-up feature to it with a email

Extracting Long text from message class with parameters
Hi,

I would like to extract the long text from a message class. However, the long text ha

Clean URLs
Hi I was wandering if anyone has ever implemented URLs on their PHP run website using URLS like wiki

This is driving me nuts!
This insert query looks to be alright, however I get this error:

QuoteYou have an error in yo

Issue Parsing XML into table
Hello all,

Im a bit new to php and new to phpfreaks. But thanks in advance for the help!
<

Create multiple (n) arrays
Hi there,

I have the following need:

I have 2 arrays (coming from a databases)

SQL Injection
In my attempts to protect my database from mySQL injection I have created another problem for myself

PHP - HTTP Digest Authentication - Understanding Code Help
Hi Everyone,

This is my first time on your website and please excuse if I am asking silly que