#36924 [NEW]: string concat

[arnout at argeweb dot nl]

From:             arnout at argeweb dot nl
Operating system: FreeBSD 5.4-RELEASE-p11
PHP version:      5.1.2
PHP Bug Type:     Scripting Engine problem
Bug description:  string concat

Description:
------------
Using the following code leaks 32 bytes of memory.

$doe = 'yoyoyo';
echo "john $doe";



PHP 5.1.2 (cli) (built: Feb 22 2006 16:17:32)
Copyright (c) 1997-2006 The PHP Group
Zend Engine v2.1.0, Copyright (c) 1998-2006 Zend Technologies
    with Zend Extension Manager v1.0.10, Copyright (c) 2003-2006, by Zend
Technologies
    with Zend Optimizer v3.0.0-Beta2, Copyright (c) 1998-2006, by Zend
Technologies


Reproduce code:
---------------
<?php

@ob_end_flush(); // to be sure


function fake1( $string ){
        echo "kaas ".$string;
}

function fake2( $string ){
        echo "kaas $string";
}

function fake3( $string ){
        $string = "kaas $string";
}

function fake4( $string ){
        echo "kaas $string asdf";
}


echo "<P><b>function fake1</b></p>";

for( $i = 0;$i < 10; $i++ ){
        echo "Memory at ".$i.": ".memory_get_usage()."<Br>\n";
        fake1( "string" );
        echo "Memory at ".$i.": ".memory_get_usage()."<Br>\n";
}

echo "<P><b>function fake2</b></p>";

for( $i = 0;$i < 10; $i++ ){
        echo "Memory at ".$i.": ".memory_get_usage()."<Br>\n";
        fake2( "string" );
        echo "Memory at ".$i.": ".memory_get_usage()."<Br>\n";
}

echo "<P><b>function fake3</b></p>";

for( $i = 0;$i < 10; $i++ ){
        echo "Memory at ".$i.": ".memory_get_usage()."<Br>\n";
        fake3( "string" );
        echo "Memory at ".$i.": ".memory_get_usage()."<Br>\n";
}

echo "<P><b>function fake4</b></p>";

for( $i = 0;$i < 10; $i++ ){
        echo "Memory at ".$i.": ".memory_get_usage()."<Br>\n";
        fake4( "string" );
        echo "Memory at ".$i.": ".memory_get_usage()."<Br>\n";
}


?>

Expected result:
----------------
Hardly any change in memory usage.

Actual result:
--------------
function fake1
Memory at 0: 42920
kaas stringMemory at 0: 42984
Memory at 1: 42984
kaas stringMemory at 1: 42984
Memory at 2: 42984
kaas stringMemory at 2: 42984
Memory at 3: 42984
kaas stringMemory at 3: 42984
...etcetera... +64 bytes, only once.

function fake2
Memory at 0: 42984
kaas stringMemory at 0: 43000
Memory at 1: 43000
kaas stringMemory at 1: 43016
Memory at 2: 43016
kaas stringMemory at 2: 43032
Memory at 3: 43032
kaas stringMemory at 3: 43048
...etcetera... +16 bytes

function fake3
Memory at 0: 43144
Memory at 0: 43160
Memory at 1: 43160
Memory at 1: 43176
Memory at 2: 43176
Memory at 2: 43192
Memory at 3: 43192
Memory at 3: 43208
...etcetera... +16 bytes

function fake4
Memory at 0: 43304
kaas string asdfMemory at 0: 43328
Memory at 1: 43328
kaas string asdfMemory at 1: 43352
Memory at 2: 43352
kaas string asdfMemory at 2: 43376
...etcetera... +24 bytes

-- 
Edit bug report at http://bugs.php.net/?id=36924&edit=1
-- 
Try a CVS snapshot (PHP 4.4): 
http://bugs.php.net/fix.php?id=36924&r=trysnapshot44
Try a CVS snapshot (PHP 5.1): 
http://bugs.php.net/fix.php?id=36924&r=trysnapshot51
Try a CVS snapshot (PHP 6.0): 
http://bugs.php.net/fix.php?id=36924&r=trysnapshot60
Fixed in CVS:                 http://bugs.php.net/fix.php?id=36924&r=fixedcvs
Fixed in release:             
http://bugs.php.net/fix.php?id=36924&r=alreadyfixed
Need backtrace:               http://bugs.php.net/fix.php?id=36924&r=needtrace
Need Reproduce Script:        http://bugs.php.net/fix.php?id=36924&r=needscript
Try newer version:            http://bugs.php.net/fix.php?id=36924&r=oldversion
Not developer issue:          http://bugs.php.net/fix.php?id=36924&r=support
Expected behavior:            http://bugs.php.net/fix.php?id=36924&r=notwrong
Not enough info:              
http://bugs.php.net/fix.php?id=36924&r=notenoughinfo
Submitted twice:              
http://bugs.php.net/fix.php?id=36924&r=submittedtwice
register_globals:             http://bugs.php.net/fix.php?id=36924&r=globals
PHP 3 support discontinued:   http://bugs.php.net/fix.php?id=36924&r=php3
Daylight Savings:             http://bugs.php.net/fix.php?id=36924&r=dst
IIS Stability:                http://bugs.php.net/fix.php?id=36924&r=isapi
Install GNU Sed:              http://bugs.php.net/fix.php?id=36924&r=gnused
Floating point limitations:   http://bugs.php.net/fix.php?id=36924&r=float
No Zend Extensions:           http://bugs.php.net/fix.php?id=36924&r=nozend
MySQL Configuration Error:    http://bugs.php.net/fix.php?id=36924&r=mysqlcfg