PHP File Handling

PHP is a popular programming language for web development, and it provides a variety of built-in functions for working with files.

We will explore some of the most commonly used functions for handling and manipulating files in PHP.

Opening and Closing Files

The first step in working with a file in PHP is to open it. The fopen() function is used to open a file.

The first argument passed to the function is the path to the file, and the second argument is the mode in which to open the file.

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

In the above example, the file example.txt is opened in read mode. Other common modes include w for write mode and a for append mode.

Once you have finished working with a file, it is important to close it using the fclose() function.

This releases any resources that were being used by the file, and ensures that any changes made to the file are saved.

fclose($file);

Reading from Files

Once a file is opened, you can start reading its contents. The fread() function is used to read a specified number of bytes from a file.

The first argument passed to the function is the file handle, and the second argument is the number of bytes to read.

$contents = fread($file, filesize("example.txt"));

In the above example, the entire contents of the example.txt file are read and stored in the $contents variable.

Another way to read from a file is by using the fgets() function. This function reads a single line from a file at a time.

The first argument passed to the function is the file handle.

while (!feof($file)) {
  $line = fgets($file);
  echo $line;
}

The above example uses a while loop to read each line of the file until the end of the file (EOF) is reached.

Writing to Files

In addition to reading from files, PHP also allows you to write to them. The fwrite() function is used to write data to a file.

The first argument passed to the function is the file handle, and the second argument is the data to be written.

$file = fopen("example.txt", "w");
fwrite($file, "Hello, world!");
fclose($file);

In the above example, the string "Hello, world!" is written to the example.txt file, and the file is closed.

Manipulating Files

PHP also provides a variety of functions for manipulating files, such as copying, moving, and deleting them.

The copy() function is used to copy a file from one location to another.

The first argument passed to the function is the path to the source file, and the second argument is the path to the destination file.

copy("example.txt", "backup/example.txt");

In the above example, the example.txt file is copied to the "backup" directory.

The rename() function is used to move or rename a file.

The first argument passed to the function is the path to the current file, and the second argument is the new path or new name for the file.

rename("example.txt", "new_example.txt");

In the above example, the example.txt file is renamed to new_example.txt.

The unlink() function is used to delete a file. The argument passed to the function is the path to the file to be deleted.

unlink("example.txt");

In the above example, the example.txt file is deleted.

Handling File Uploads

When working with forms on a web page, it is often necessary to handle file uploads.

PHP provides a number of built-in functions for handling file uploads, such as is_uploaded_file() and move_uploaded_file().

The is_uploaded_file() function checks whether a file has been uploaded through a form.

The argument passed to the function is the path to the file.

if (is_uploaded_file($_FILES["file"]["tmp_name"])) {
  // File has been uploaded
} else {
  // File was not uploaded
}

In the above example, the is_uploaded_file() function is used to check whether the file in the "file" field of the $_FILES array has been uploaded.

The move_uploaded_file() function is used to move an uploaded file from its temporary location to a permanent location.

The first argument passed to the function is the path to the temporary file, and the second argument is the path to the permanent file.

move_uploaded_file($_FILES["file"]["tmp_name"], "uploads/file.txt");

In the above example, the file in the "file" field of the $_FILES array is moved from its temporary location to the "uploads" directory and renamed to file.txt.

Takeaways

PHP provides a wide range of built-in functions for working with files. From opening, reading, writing and closing files, to manipulating and handling file uploads, PHP makes it easy to work with files in your web applications.

Understanding how to use these functions correctly can help you to build more powerful and efficient applications.

PHP Basics