[Vtigercrm-developers] A question on efficiency/semantics...

[Mariusz Krzaczkowski | YetiForce Sp. z o.o.]

Notice: Undefined variable /  Undefined index / Undefined offset

This is a bug that causes a lot of problems,
no one knows if it's on purpose or if someone forgot to change something 
or made a typo.

https://stackoverflow.com/questions/4261133/notice-undefined-variable-notice-undefined-index-and-notice-undefined#answer-4261200

 From the vast wisdom of the PHP Manual [6]:

> Relying on the default value of an uninitialized variable is 
> problematic in the case of including one file into another which uses 
> the same variable name. It is also a major security risk [1] with 
> register_globals [2] turned on. E_NOTICE [3] level error is issued in 
> case of working with uninitialized variables, however not in the case 
> of appending elements to the uninitialized array. isset() [4] language 
> construct can be used to detect if a variable has been already 
> initialized. Additionally and more ideal is the solution of empty() [5] 
> since it does not generate a warning or error message if the variable 
> is not initialized.

--

Z poważaniem / Kind regards
Mariusz Krzaczkowski

W dniu 2021-05-05 17:36, Alan Lord napisał(a):

> Interesting.
> 
> That seems like good/valid Warning - it should encourage the 
> declaration of variables at the start of each routine.
> 
> Maybe for a variable variable it might not make sense but those aren't 
> that common it seems to me?
> 
> Nice to hear from you Joe. Hope all's well.
> 
> Cheers
> 
> Al
> 
> On 05/05/2021 16:24, Joe Bordes wrote:
> 
>> Sadly, PHP warning system doesn't work that way:
>> 
>> ----
>> 
>> <?php
>> error_reporting(-1);
>> ini_set('display_errors', 1);
>> 
>> if ($nothere) {
>> echo "it is here";
>> } else {
>> echo "it isn't here";
>> }
>> -----
>> 
>> result
>> 
>> -----
>> 
>> joe at linuxmint:/var/www/coreBOSTest$ php k.php
>> PHP Notice:  Undefined variable: nothere in /var/www/coreBOSTest/k.php 
>> on line 5
>> PHP Stack trace:
>> PHP   1. {main}() /var/www/coreBOSTest/k.php:0
>> 
>> Notice: Undefined variable: nothere in /var/www/coreBOSTest/k.php on 
>> line 5
>> 
>> Call Stack:
>> 0.0001     393600   1. {main}() /var/www/coreBOSTest/k.php:0
>> 
>> it isn't here
>> 
>> ------
>> 
>> so you get the warning if the variable is not defined which is what 
>> you are trying to avoid
> 
> _______________________________________________
> http://www.vtiger.com/


Links:
------
[1] http://www.php.net/manual/en/security.globals.php
[2] http://www.php.net/manual/en/ini.core.php#ini.register-globals
[3] 
http://www.php.net/manual/en/errorfunc.constants.php#errorfunc.constants.errorlevels.e-notice
[4] http://www.php.net/manual/en/function.isset.php
[5] http://php.net/manual/en/function.empty.php
[6] http://php.net/manual/en/language.variables.basics.php#example-112
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