Mastering PHP’s file_put_contents(): Write, Append, and Stream Data Efficiently

In PHP development, handling files is common, and the file_put_contents() function provides a simple, efficient way to write data without manually opening and closing files.

Syntax

file_put_contents(string $filename, mixed $data, int $flags = 0, resource $context = null): false|int

Parameter description

$filename

: target file name. $data: data to write; can be a string, array, or a callback returning a string. $flags: optional flags, default 0 (no extra options). $context: optional stream context resource.

Return value

On success, returns the number of bytes written.

On failure, returns false.

Usage examples

Write a string

$filename = 'test.txt';
$data = 'Hello, world!';
file_put_contents($filename, $data);

This creates test.txt and writes the string "Hello, world!" into it.

Append a string

$filename = 'test.txt';
$data = 'Hello, world again!';
file_put_contents($filename, $data, FILE_APPEND);

Using the FILE_APPEND flag appends the string to the existing file.

Write an array

$filename = 'test.txt';
$data = ['apple', 'banana', 'orange'];
file_put_contents($filename, implode("
", $data));

The array elements are joined with newline characters and written to test.txt.

Write using a callback

$filename = 'test.txt';
$data = function() {
    return date('Y-m-d H:i:s');
};
file_put_contents($filename, $data());

An anonymous function returns the current timestamp, which is then written to the file.

Additional tips

Combine with fopen(), fwrite(), and fclose() for finer control.

Read existing content with file_get_contents() and then write new data using file_put_contents().

The file_put_contents() function simplifies file operations in PHP, handling strings, arrays, and callbacks, and supports both overwriting and appending with minimal code.