'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

OPINIONS WANTED
This is my login page code, and I want your opinion on it please!

Code: // Login ~ CHECKS

Multi-image upload problems
Lets see if I can get some help on this one. Can anyone show me what I am doing wrong here. I'm just

animation progress while uploading files?
Hello, i have some website form to upload few files to server. i want to put some gif animation whi

reading xml faster than DB call?
I am trying to optimize a high traffic website, and I enabled a feature where there are three photos

GIS appliction help
I found some tutorials in the internet to develop a map application I don't want to use google maps

upload image name with extension using php
hi frds..

<input id="file1" type="file" name="file[]" &a

Date Format
Hi there,

I have a date format like this right now:
Sat, 17 Oct 2009 17:04:00

I ne

php code generators
All

Whilst enjoying learning a new language i have come accross a number of free code generat

Could Someone Please Debug This?
I was wondering if someone could debug this script for me. I realize it's not the tidest script (and

Login script (probably a simple error)
dbConfig.php
Code: <?
// Replace the variable values below
// with your specific dat