AI Overview
To write a file using PHP, the file_put_contents() function provides a concise method for writing data to a file. Alternatively, you can use the fopen(), fwrite(), and fclose() functions for more granular control.
Using file_put_contents():
The file_put_contents() function simplifies writing to a file by handling the opening, writing, and closing in a single call.
Code

<?php
$filename = "example.txt";
$content = "This is some content to write to the file.";

// Write the content to the file. If the file doesn't exist, it will be created.
// If it exists, its content will be overwritten.
if (file_put_contents($filename, $content) !== false) {
   echo "File written successfully using file_put_contents().";
} else {
   echo "Error writing file using file_put_contents().";
}

// To append to an existing file without overwriting, use the FILE_APPEND flag:
$append_content = "\nThis content is appended.";
if (file_put_contents($filename, $append_content, FILE_APPEND) !== false) {
   echo "\nContent appended successfully.";
} else {
   echo "\nError appending content.";
}
?>

Using fopen(), fwrite(), and fclose():
This method offers more control, especially for larger files or specific file handling scenarios.
Code

<?php
$filename = "another_example.txt";
$content = "This is content written using fopen, fwrite, and fclose.";

// Open the file in write mode ('w'). If the file doesn't exist, it will be created.
// If it exists, its content will be truncated (emptied).
$file_handle = fopen($filename, 'w');

if ($file_handle) {
   // Write the content to the file.
   fwrite($file_handle, $content);

   // Close the file.
   fclose($file_handle);

   echo "File written successfully using fopen, fwrite, and fclose.";
} else {
   echo "Error opening or writing the file.";
}

// To append to an existing file, open it in append mode ('a'):
$append_content = "\nMore appended content.";
$file_handle_append = fopen($filename, 'a');

if ($file_handle_append) {
   fwrite($file_handle_append, $append_content);
   fclose($file_handle_append);
   echo "\nContent appended successfully using 'a' mode.";
} else {
   echo "\nError appending content using 'a' mode.";
}
?>

Important Considerations:

   File Permissions:
   Ensure the directory where you are creating or writing the file has the necessary write permissions for the web server user.
   Error Handling:
   Always include error handling (e.g., checking return values of functions) to manage potential issues like file not found, permission errors, or disk full conditions.
   File Modes:
   Choose the appropriate file mode for fopen() based on your needs:
       'w' (write): Opens for writing, creates if not found, truncates if found.
       'a' (append): Opens for writing, creates if not found, appends to the end if found.
       'x' (exclusive create): Creates and opens for writing, fails if file exists.
       'c' (create if not found): Opens for writing, creates if not found, does not truncate if found.