php.net |  support |  documentation |  report a bug |  advanced search |  search howto |  statistics |  random bug |  login

go to bug id or search bugs for

Bug #51739 tricky string to float conversion
Submitted: 2010-05-04 15:07 UTC Modified: 2010-05-04 15:15 UTC
From: daniel dot buschke at nextiraone dot de Assigned:
Status: Not a bug Package: *General Issues
PHP Version: 5.2.13 OS:
Private report: No CVE-ID: None
View Developer Edit
Welcome back! If you're the original bug submitter, here's where you can edit the bug or add additional notes.
If you forgot your password, you can retrieve your password here.
Password:
Status:
Package:
Bug Type:
Summary:
From: daniel dot buschke at nextiraone dot de
New email:
PHP Version: OS:

 

 [2010-05-04 15:07 UTC] daniel dot buschke at nextiraone dot de 
Description:
------------
If you convert a string like 8315e839da08e2a7afe6dd12ec58245d into a float the conversion results in float(INF). The conversion seems to use only 8315e839 and throws anything else away.

$ php -r 'var_dump(time()+rand()+"8315e839da08e2a7afe6dd12ec58245d");'
float(INF)

Converting this string into a float is - of course - a bug of my PHP script. But at least I would like to discuss about the conversion behavior. It is fully correct to convert this string into a float if it is just "8315e839" but throwing some data away is - from my point of view - not a valid behavior.

Test script:
---------------
var_dump((float)"8315e839da08e2a7afe6dd12ec58245d");

Expected result:
----------------
false or null or some other invalid "floats" or a warning

Actual result:
--------------
float(INF)

Patches

Pull Requests

History

AllCommentsChangesGit/SVN commitsRelated reports
 [2010-05-04 15:15 UTC] aharvey@php.net
-Status: Open +Status: Bogus
 [2010-05-04 15:15 UTC] aharvey@php.net 
This is expected and documented behaviour: string to float conversions will use any valid numeric data at the start of the string and ignore anything thereafter. The e is being processed because it's being treated as an exponent.

More information:
http://php.net/language.types.string#language.types.string.conversion
 [2010-05-05 09:27 UTC] daniel dot buschke at nextiraone dot de 
look at this: 8315e839da08e2a7afe6dd12ec58245d

- 8315 is a valid integer
- e is the sign for an exponent
- BUT: 839da08e2a7afe6dd12ec58245d is not an integer! So it is not a valid exponent!
 
PHP Copyright © 2001-2025 The PHP Group
All rights reserved. 		Last updated: Thu Jan 02 13:01:30 2025 UTC