Using PHP's fwrite() Function to Write Data to Files

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

Syntax of fwrite()

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

Parameter Explanation

file : required; the file handle returned by fopen() .

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

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

fwrite() Usage Example

The following example demonstrates writing a simple string to a file:

<code>&lt;?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!";
}
?&gt;</code>

This code opens test.txt for writing, writes the string "Hello, World!", closes the file, and outputs a success or failure message.

Writing Arrays and Other Data Types

Beyond strings, fwrite() can write arrays or other data types after serialization. The example below writes a serialized array to a file:

<code>&lt;?php
$file = fopen("data.txt", "w");
if ($file) {
    $data = array("Zhang San", "Li Si", "Wang Wu");
    fwrite($file, serialize($data)); // write serialized array
    fclose($file);
    echo "Write successful!";
} else {
    echo "Unable to open file!";
}
?&gt;</code>

Here, an array containing three elements is serialized with serialize() and then written to data.txt .

The fwrite() function is a practical tool for file output in PHP; when using it, ensure the file is opened with the correct mode and that the data type matches the intended write operation.