How to Write Files in PHP Using fputs(): Syntax, Parameters, and Example

Function Syntax

The PHP fputs() function writes a string to an open file handle. It is an alias of fwrite().

fputs ( resource $handle , string $string [, int $length ] ) : int|bool

Parameters

$handle – A valid file resource obtained from fopen() (or another function that returns a stream).

$string – The data to be written to the file.

$length (optional) – The maximum number of bytes to write. If omitted, the entire length of $string is written.

Return Value

On success the function returns the number of bytes actually written. On failure it returns false.

Example

<?php
$file = fopen("demo.txt", "w"); // open for writing, creates file if it does not exist
if ($file) {
    $content = "Hello, World!";
    $bytesWritten = fputs($file, $content); // write the string
    if ($bytesWritten !== false) {
        echo "Write successful, wrote {$bytesWritten} bytes.";
    } else {
        echo "Write failed.";
    }
    fclose($file); // always close the handle to free the resource
}
?>

Important Notes

The file must be opened with a mode that permits writing (e.g., "w", "a", "r+", etc.).

Always close the file with fclose() after writing to release the underlying resource.

If you need to write binary data, use a binary mode such as "wb" on Windows.

When $length is specified and is smaller than the string length, only the first $length bytes are written.