Using PHP file_put_contents() to Write Data to Files

PHP provides the file_put_contents() function for writing data to files, accepting up to four parameters: the filename, the data, optional flags, and an optional context resource.

Function syntax:

<code>int file_put_contents ( string $filename , mixed $data [, int $flags = 0 [, resource $context ]] )</code>

Writing a string to a file

<code>$file = "test.txt";
$data = "Hello, world!";
file_put_contents($file, $data);
</code>

Running this code creates test.txt in the current directory with the content "Hello, world!".

Writing an array to a file

<code>$file = "users.txt";
$data = array(
    array("name" => "John", "age" => 25),
    array("name" => "Emma", "age" => 28),
    array("name" => "Michael", "age" => 31)
);
file_put_contents($file, var_export($data, true));
</code>

The array is converted to a string with var_export() before being written. After execution, users.txt contains a PHP‑style array representation of the data.

Flag options

FILE_USE_INCLUDE_PATH : Search for the file using the include_path.

FILE_APPEND : Append data to the end of the file instead of overwriting.

LOCK_EX : Acquire an exclusive lock while writing to prevent concurrent writes.

Example of appending data:

<code>$file = "log.txt";
$data = "New log entry";
file_put_contents($file, $data, FILE_APPEND);
</code>

This adds "New log entry" to log.txt without erasing existing content.

Context parameter

The fourth parameter allows passing a stream context for more advanced file operations; details can be found in the PHP documentation.

Summary

Using file_put_contents() , developers can easily write strings or arrays to files, control behavior with flags such as FILE_APPEND and LOCK_EX , and optionally provide a context for complex scenarios.