Using PHP fwrite() to Write Data to Files

In PHP, the fwrite() function is used to write data to a file, offering a simple and flexible way to handle common file‑writing tasks.

Syntax

<code>fwrite(file, string, length)</code>

Parameters

file : required file handle returned by fopen() .

string : required data to write; can be a string, array, or other type.

length : optional maximum number of bytes to write; defaults to the length of the data.

Example – Writing a String

The following example opens test.txt for writing, writes the string “Hello, World!”, and closes the file.

<code><?php
$file = fopen("test.txt", "w"); // open file in write mode
if ($file) {
    $content = "Hello, World!"; // content to write
    fwrite($file, $content); // write to file
    fclose($file); // close file
    echo "Write successful!";
} else {
    echo "Unable to open file!";
}
?></code>

This script demonstrates using fopen() to obtain a file handle, fwrite() to write data, and fclose() to release the resource.

Example – Writing an Array

The next example serializes an array and writes it to data.txt .

<code><?php
$file = fopen("data.txt", "w");
if ($file) {
    $data = array("张三", "李四", "王五");
    fwrite($file, serialize($data)); // write serialized array
    fclose($file);
    echo "Write successful!";
} else {
    echo "Unable to open file!";
}
?></code>

By serializing the array with serialize() , the data can be stored in a file and later retrieved.

Overall, fwrite() is a practical function for writing strings, arrays, or other data types to files, provided the file is opened with an appropriate mode.