__halt_compiler

(PHP 5 >= 5.1.0)

__halt_compiler Halts the compiler execution

Description

void __halt_compiler ( void )

Halts the execution of the compiler. This can be useful to embed data in PHP scripts, like the installation files.

Byte position of the data start can be determined by the __COMPILER_HALT_OFFSET__ constant which is defined only if there is a __halt_compiler() presented in the file.

Return Values

No value is returned.

Examples

Example #1 A __halt_compiler() example

<?php

// open this file
$fp fopen(__FILE__'r');

// seek file pointer to data
fseek($fp__COMPILER_HALT_OFFSET__);

// and output it
var_dump(stream_get_contents($fp));

// the end of the script execution
__halt_compiler(); the installation data (egtargzPHPetc.)

Notes

Note:

__halt_compiler() can only be used from the outermost scope.

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User Contributed Notes 5 notes

up
6
-T-
6 months ago
What zsh mentioned six years ago: "Also, it cannot be used in eval() -- it won't throw a syntax error, but it won't do anything either." is wrong. It can be used in eval() -- it will halt the eval.
up
4
ravenswd at gmail dot com
3 years ago
__halt_compiler is also useful for debugging. If you need to temporarily make a change that will introduce an error later on, use __halt_compiler to prevent syntax errors. For example:

<?php
if ( $something ):
  print
'something';
endif;  
// endif placed here for debugging purposes
__halt_compiler();
endif;  
// original location of endif -- would produce syntax error if __halt_compiler was not there
?>
up
1
zsh
6 years ago
__halt_compiler() is a language construct and therefore cannot be used as a variable function.

Also, it cannot be used in eval() -- it won't throw a syntax error, but it won't do anything either.
up
-3
Anonymous
4 months ago
This is not what people expect to see on manual pages, don't take this as example.
up
-22
Ultimater at gmail dot com
4 years ago
Another possible usage, in addition to binary data and installers,
is using it to separate model, view and controller logic from one another:

<?php
class viewhelper{function render(){
eval(
file_get_contents(__FILE__,null,null,__COMPILER_HALT_OFFSET__));
}}

//database logic goes here
$row=array(
'loggedin'=>true,
'modcp'=>true,
'admincp'=>false,
'username'=>'Ultimater',
'userid'=>1234
);
//database logic goes here

//controller logic goes here
$view=new viewhelper;
$view->title="Test -> Ultimater's MVC example";
$view->base="http://".$_SERVER['HTTP_HOST'];
$view->username=$row['username'];
$view->userid=$row['userid'];
$view->authbar->loggedin=$row['loggedin'];
$view->authbar->modcp=$row['modcp'];
$view->authbar->admincp=$row['admincp'];
$view->render();
//controller logic goes here

__halt_compiler();?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title><?=htmlentities($this->title)?></title>
<style type="text/css">
a{color:#3333ff;text-decoration:none;}
a:hover{color:#0380fc;}
</style>
</head>
<body>
<?php
if($this->authbar->loggedin){
?>
<table><tr>
<td>Hello <a href="<?=$this->base?>/showuser.php?id=<?=$this->userid?>
"><?=htmlentities($this->username)?></a></td><td>[</td>
<td><a href="<?=$this->base?>/logout.php">Log Out</a></td>
<th><a href="<?=$this->base?>/usercp.php">UserCP</a></th>
<? if($this->authbar->modcp){ ?>
<td>&middot;</td><th><a href="<?=$this->base?>/modcp.php">ModCP</a></th>
<? } ?>
<? if($this->authbar->admincp){ ?>
<td>&middot;</td><th><a href="<?=$this->base?>/admincp.php">AdminCP</a></th>
<? } ?>
<td>]</td>
</tr></table>
<?php
}else{
?>
<table><tr><td>Hello Guest</td><td>[</td>
<td><a href="<?=$this->base?>/login.php">Log In</a></td>
<th><a href="<?=$this->base?>/register.php">Register</a></th>
<td>]</td></tr></table>
<? } ?>
</body>
</html>
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