'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

problems with php variables in mysql query
i can't seem to get the following query to work.

select $q1c from $vote_rate where id = $re

Help with ORDER BY
Hello. I would like to order by ascending States, then Cities, then Gyms in the following code, but

TimeZoneOffset
Hello,

Please i need your help. I have a system that users can use to punch in and out. This

Edit MySQL Row Using PHP and HTML Form
Hello,

Here's what I'm trying to do. Build a page where a user enters a MySQL row number in.

Production of mango in processing industry
Hi,

We have one scenario ,company is in process industry,they are manufacturing MANGO pul

MVC - Code review
I'm in the process of trying to wrap my head around MVC, and as part of that, I'm attempting to impl

php mail form text wont appear / javascript included
Guys/gals...

I am running into a problem whereby I have a great piece of javascript code that

PHP error (line 38) my website
Hello everyone, I'm new on this
and I got a web site thats got a error not showing the photos on<

Weird problem with SELECT command..Help!
Hi!

It seems I'm having a really weird problem with SQL SELECT command....I have table into a

Aris, Netweaver BPM, Visual composer and X'app
Dear Experts,

Whats the relationship between the following components: Aris, Netweaver BP