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English
__halt_compiler() is a special language structure in PHP. Its function is to stop the compiler's parsing and execution of subsequent code immediately when the code is executed to the function. That is to say, the content after __halt_compiler() will not be executed as PHP code, but can be directly retained as data in the script file.
Stop the PHP compiler to continue reading and executing the subsequent code.
Allows to include arbitrary data at the end of the script, often used to embed binary data or custom meta information.
It can only be used once, and cannot be used with parameters.
<?php
echo "Start execution\n";
__halt_compiler();
echo "This code will not be executed\n";
// You can also put some custom data later
The typical use of __halt_compiler() is to create self-contained PHP files, such as PHAR archives or to embed data directly into scripts.
exit() (or equivalent die() ) is a function used in PHP to terminate script execution. The program stops running immediately after being called, and a status code or string can be passed as output.
Stop script execution immediately.
You can output prompt information or return an integer status code.
Usually used to force stop after encountering an error or completing a task.
<?php
echo "Start execution\n";
if (!file_exists("config.php")) {
exit("The configuration file does not exist，Program termination\n");
}
echo "The configuration file exists，Continue to execute\n";
exit() is ideal for process control, stopping scripts when encountering fatal errors, or returning program execution status in CLI environment.
| aspect | __halt_compiler() | exit() |
|---|---|---|
| Function | Stop the compiler to parse subsequent code and retain subsequent data | Stop script execution immediately and output message or status code |
| Whether to execute subsequent code | No subsequent code execution | No subsequent code execution |
| Subsequent code/data processing | Subsequent code is considered raw data and can be read or processed | The subsequent code will not be processed |
| Typical uses | Embed data, self-contained files, PHAR archives | Termination of execution, error handling, process control |
| Can it be used multiple times | Only use once | Can be called multiple times |
| Whether to bring parameters | Can't bring parameters | Can take parameters (string or integer) |
Embed custom data <br> When you need to attach data directly to a PHP script file, such as packaging resources or configuration, you can use it to preserve the data area without being interpreted by PHP.
Make PHAR files
The PHAR format is essentially a self-contained PHP archive file that uses __halt_compiler() to merge archive data and code.
Prevent code execution <br> Used to prevent the code from being executed unexpectedly and ensure that subsequent data will not be parsed by PHP.
Error handling and exception termination <br> When an error that cannot be recovered is encountered, use exit() to directly stop the program and prompt the user.
Command line script control flow <br> In CLI scripts, a specific status code is returned based on the execution results, which facilitates automated call and management of the script.
Process aborted <br> Abort program execution when certain conditions are met to avoid continuing to execute invalid or dangerous code.
In summary, although __halt_compiler() and exit() can both terminate the execution of PHP code, __halt_compiler() is more like a tool for data embedding, while exit() is an important function for controlling flow and handling exceptions in daily development. Understanding their differences and uses can help developers write more robust and flexible PHP programs.
