'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

PHP4 to PHP5 Conversion
Hi Everyone,

I am working on a site that is built up on PHP4 and each page is being started f

Working with Global Variables
hi, I'm not really sure why the following code is returning a "Call to a member function getBan

Parse error: syntax error, unexpected T_ELSEIF in /home/......html/item.php on l
I do not know what is wrong with this. Hope some one can help. I do nto want to post the entire site

Find current logon time
Hi,
in my sql script i want to query and find out the logon time of the current session.
<

Converting from one format to another
"I have got a date in DD/MM/YYYY but I need it in MM-DD-YYYY. Help!"

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

Problem writing URL into database
How would I write this into the database?

<?php echo "http://".$_SERVER['SER

listing help
Hi,

at first, great new design!!! I like it,

i got a problem,

I want to list so

Lack of simpleXML Documentation
What is up with this.

Look at: http://www.php.net/manual/en/function.simplexml-load-file.php<

About imagecopyresampled()
Hello,

I am looking to use this function to resize parts of an image to a fixed thumbnail siz