Bug #417 [Com]: silent (?) change in variable's value behaviour

Edit report at https://bugs.php.net/bug.php?id=417&edit=1

 ID:                 417
 Comment by:         spam2 at rhsoft dot net
 Reported by:        jan at nrw dot net
 Summary:            silent (?) change in variable's value behaviour
 Status:             Closed
 Type:               Bug
 Package:            Misbehaving function
 Operating System:   Linux 2.0.33, BSDI 3.1
 PHP Version:        3.0 Release Candidate 5
 Assigned To:        zeev
 Block user comment: N
 Private report:     N

 New Comment:

yeah because '0' is *not* empty when it is a string '' would be empty

hence you should cast expected integers with (int)$var and also consider the scalar type hints and return types introduced in PHP7


Previous Comments:
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[2017-03-31 09:51:33] hugo at domibay dot es

I found by the Years the PHP Programmer Community has come about with different workaround for this issue:

if(strlen($string) > 0)
  echo "string is empty\n";

but for text with non latin characters you need the mb_strlen() Function to savely check the string.

if(mb_strlen($string) > 0)
  echo "string is empty\n";

Then I also found other solutions like

if(isset($string) && $string !== "")
  echo "string is empty\n";

if(is_numeric($string) || isset($string[0]))
  echo "string is empty\n";

I found that (NULL !== "") would result as "true"
so I needed to add isset() to the check.

Then if the variable would be a Number like $string = 5 
the Check (isset($string[0])) would result as "false" because this Check does not work for numbers
so I needed to add is_numeric($string) to the check.

But adding all those additional checks to get the right Behaviour results in performance drop downs.

So that I finally got the right result with an acceptable performance with the Check

if(isset($string) && $string !== "")
  echo "string is empty\n";

------------------------------------------------------------------------
[2017-03-31 09:05:21] hugo at domibay dot es

This Behaviour still persists in PHP 5.6 on Centos7

I am running constantly into the same problem:

The Documentation states on 
http://php.net/manual/en/function.empty.php
The Function empty() would trigger on Values like
0 (0 as an integer)
0.0 (0 as a float)
"0" (0 as a string)
as empty($var) === true

But I found in many cases a String containing a "0" is not empty. It contains a Character that is "0".
If I store the Character "0" into a file the file is not empty anymore it contains the text "0".
For example:
$ echo "0" > myfile.txt

On Integers the Value 0 can be a valid number according to the Programming Logic as an Index of an Array for example.
The same goes for Float Numbers.

I found discarding those Values as "empty" is an Error in most cases of a complex Application.

Test script: 
This Script might be simple but it leads to silent Application Errors that are hard to track down.
https://pastebin.com/gjJwHe4T

Actual result:
The Script will print only:
'1' => '2'
The other 2 Entries are silently rejected because of the Values "0".

Expected result:
The Script should print out:
'0' => '1'
'1' => '2'
'3' => '0'
On Strings only Values of NULL or "" should trigger empty($var) === true
On Integers only Values of NULL should trigger empty($var) === true
On Float Numbers only Values of NULL should trigger empty($var) === true

------------------------------------------------------------------------
[1998-05-29 18:20:11] rasmus

Fixed by Zeev

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[1998-05-29 17:54:01] jan at nrw dot net

I'm not sure if this is to be called a bug or a feature, but this is the problem i have:

- i wrote some apps in PHP3RC4, with excessive use of forms and PHP3-scripts which get form fields POSTed.
These scripts contain many value-checks like "if ($form_field1) do something;" this worked like i expected - empty 
fields in the form resulted in "False" in the above statement.
I then upgraded to PHP3RC5 - and now empty form fields result in "True". I realized the new function "empty()" 
and changed scripts to use this funktion, but now a form-input of "0" results in "empty()=True". 
This behaviour is against all i'm used to in other scripting languages, i must say. Also, i'm not sure what the 
intentional use of "empty()" is - a string or Value of "0" isn't an empty variable container for me... or am i totally wrong here?

At least, i really would like to know what the intentional behaviour of PHP3/form fields/variables/empty()/if() 
is or should be. 
Apart from that - PHP3 becomes better and better! It's a pleasure writing apps for the web with it!

thanks for any help/hint, Jan


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