42. Introduction to File System Operations
PHP is often used to interact with the server's filesystem, managing files, logs, and configuration data.
1. Reading Files (file_get_contents)
The simplest way to read an entire file into a string.
php
<?php $filename = "data.txt"; // Assume data.txt contains: Hello World if (file_exists($filename)) { $content = file_get_contents($filename); echo "File Content: " . $content; } else { echo "Error: File not found."; } ?>2. Writing to Files (file_put_contents)
Writes a string to a file. If the file doesn't exist, it is created. By default, it overwrites the content.
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<?php $new_data = "This is a new line."; // Overwrite existing content file_put_contents("log.txt", $new_data); // Append (add to the end) using a flag file_put_contents("log.txt", "\nAnother log entry.", FILE_APPEND); ?>3. Advanced File Handling (Opening Streams)
For large files or precise control, we use fopen(), fwrite(), and fclose().
| Function | Description |
|---|---|
fopen($file, $mode) | Opens the file stream in a specific mode (w=write, a=append, r=read). |
fwrite($handle, $string) | Writes content to the open file. |
fgets($handle) | Reads a single line from the file. |
fclose($handle) | Closes the file stream, releasing server resources. |
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<?php $file = fopen("temp.txt", "w"); fwrite($file, "Writing stream data."); fclose($file); ?>