PHP file_put_contents() Function: Usage and Examples

file_put_contents() Function is one of the PHP operations used in filesystem and stream workflows. Writes a string to a file, optionally with flags. The examples below show what it does and how to handle its result.

What Is file_put_contents() Function?

Writes a string to a file, optionally with flags.

Its syntax is:

file_put_contents(string $filename, mixed $data, int $flags = 0, $context = null)

The parameters are:

• string $filename — The source or destination filesystem path.
• mixed $data — The bytes or value being written.
• int $flags = 0 — Option constants that alter how the operation behaves.
• $context = null — Optional PHP stream context controlling relevant stream or wrapper behavior.

Return value: The declared return type is int|false. By default it overwrites the file; LOCK_EX helps coordinate cooperating writers.

Important: By default it overwrites the file; LOCK_EX helps coordinate cooperating writers.

Example 1: Basic Usage

The basic example focuses on the behavior of file_put_contents() Function: writes a string to a file, optionally with flags. Inputs are defined locally or shown as application-controlled paths.

<?php

$filePath = sys_get_temp_dir() . "/demo-write.txt";
$bytesWritten = file_put_contents($filePath, "Ready\n", LOCK_EX);
var_dump($bytesWritten !== false);
unlink($filePath);

The displayed value, file content or return status depends on the input and surrounding environment. Results involving local paths, identifiers or generated files are not fixed values.

Example 2: A Different Use Case

This second example illustrates another input or execution condition for file_put_contents() Function. Notice the different checks, arguments, or output handling.

<?php

$path = sys_get_temp_dir() . "/append-demo.txt";
file_put_contents($path, "First\n");
file_put_contents($path, "Second\n", FILE_APPEND | LOCK_EX);
echo file_get_contents($path);
unlink($path);

This variation matters because by default it overwrites the file; LOCK_EX helps coordinate cooperating writers.

Practical Example: Using the Operation in an Application

The following example demonstrates how file_put_contents() Function fits into a more complete file or archive workflow, including inputs and appropriate checks.

<?php

$logFile = sys_get_temp_dir() . "/batch-log.txt";
$written = file_put_contents($logFile, date("c") . " Task completed\n", FILE_APPEND | LOCK_EX);
if ($written === false) { throw new RuntimeException("Log write failed"); }

The operation shown is an illustrative script. Adapt the filenames, required permissions, and error handling to your own controlled application environment before running it.

Important Behavior and Edge Cases

• Function behavior: Writes a string to a file, optionally with flags.
• Limitation: By default it overwrites the file; LOCK_EX helps coordinate cooperating writers.

Comparison With Related Functions

Use file_put_contents() Function for the specific behavior described above. The related operation, fwrite(), serves a different purpose; do not substitute it unless that different behavior is intended.

Common Beginner Mistakes

Key Takeaways

• Writes a string to a file, optionally with flags.
• By default it overwrites the file; LOCK_EX helps coordinate cooperating writers.
• Related operation: fwrite() — Writes to an existing stream; file_put_contents() opens and closes the target internally.

file_put_contents() Function is useful when its specific behavior matches your application requirement. Keep paths controlled, check failures, and handle environment-dependent operations deliberately.