fopen() in PHP

fopen() is used to open a file or a URL in PHP. It prepares the file so you can read from it, write to it, or both, depending on the mode you choose.

Syntax:

fopen(filename, mode, include_path, context)

Common File Modes:

Basic Examples:

1. Open a file for reading

<?php
$file = fopen("example.txt", "r");

if ($file) {
    echo "File opened successfully.";
    fclose($file);
} else {
    echo "Unable to open file.";
}
?>

Here, example.txt must already exist. Otherwise, fopen() returns false.

2. Open a file for writing (and overwrite contents)

<?php
$file = fopen("newfile.txt", "w");

if ($file) {
    fwrite($file, "Hello, World!");
    fclose($file);
    echo "File written successfully.";
} else {
    echo "Unable to open file.";
}
?>

If newfile.txt exists, it will be cleared first.
If it doesn’t exist, PHP will create it.

3. Open a file for appending (writing at the end)

<?php
$file = fopen("log.txt", "a");

if ($file) {
    fwrite($file, "New log entry at " . date("Y-m-d H:i:s") . "\n");
    fclose($file);
    echo "Log updated.";
} else {
    echo "Unable to open log file.";
}
?>

Appending is good for logs because new data is added at the end without deleting the old data.

4. Trying to open a file that doesn’t exist (reading mode)

<?php
$file = fopen("nonexistent.txt", "r");

if ($file) {
    echo "File opened.";
    fclose($file);
} else {
    echo "File does not exist!";
}
?>

Since we are using r, the file must exist, otherwise we get false.

Important:

• Always use fclose($file); after finishing with a file to free up resources.
• Always check if fopen() was successful before doing anything.
• You can use feof(), fgets(), fwrite(), and other file functions after using fopen().