File Handeling

File handling plays a very important role while storing & retrieving a wide variety of data. Several functions are there for creating, editing, reading and uploading files.

Opening a file

fopen() function is used to open files in PHP. By using this method, a file can be opened in various modes.

fopen() syntax

// syntax
fopen(filename, mode);

Code example:

<?php
	$file = "d:\\file.txt";
	$pointer = fopen($file, "r");
	fclose($pointer);
?>

Reading and Closing a file

There are various functions in PHP to read a file. These functions allow us to read the data line by line, character by character or all file data at once. These functions are:

fread(): This method reads the data from an open file. 

// syntax
fread(stream, length);

// UNDERSTANDING OF SYNTAX
// stream: A file system pointer resource that is created using fopen().
// length: length of byte to be read.

Code Example

<?php
	$file = "d:\\file.txt";
	$pointer = fopen($file, "r");
	$content = fread($pointer, filesize($file));
	fclose($pointer);		// closing file
?>

fgets(): This method reads a single line from the file.

// syntax
fgets(stream, length);		

// UNDERSTANDING SYNTAX
// stream: A file system pointer resource that is created using fopen().
// length: Reading ends when (length-1) bytes are read or a newline or an EOF occurs.

Code Example

<?php
	$file = "d:\\file.txt";
	$pointer = fopen($file, "r");   // opening file
	echo fgets($pointer);  // reading file
	fclose($pointer);	// closing file
?>

fgetc(): This method reads a single character from the file.

// syntax
fgetc(stream);		

// UNDERSTANDING SYNTAX
//stream: A file system pointer resource that is created using fopen().

Code Example

<?php
	$file = "d:\\file.txt";
	$pointer = fopen($file, "r");
	while( !feof($file)) {		//  Check End Of File (EOF)
		echo fgetc($file);
	}
	fclose($pointer);	// closing a file
?>

Writing a file

fwrite() method is used to write to a file.

// syntax
fwrite(stream, string, length);

Understanding syntax

stream: A file system pointer resource created using fopen().

string: A string to be written.

length: If this argument is given, writing will stop specified bytes are written or the end of string is reached. 

Code Example

<?php
	$file = fopen("file.txt", "w");
	fwrite($file, "Writing String to a file…\n");
	fwrite($file, "Adding another line…\n");
	fclose($file);
?>

Overwriting a file

file.txt is now composed of above mentioned data and if we will open this existing file in a writing mode, the existing data will get erased and a new file will be there to write again.

Code Example

<?php
	$file = fopen("file.txt", "w");
	$txt = "Mickey Mouse\n";
	fwrite($file, "New text…..\n");
	fclose($file);
?> 

Now, the file.txt file will contain “New text….” as its content. In a similar way, we can open a file in append mode to truncate the data into a file rather than erasing the older data. 

// for example
$file = fopen("file.txt", "a");

Deleting a file

unlink() function is used to delete a file.

// syntax
unlink(filename);

// ***It will return TRUE, if the file is deleted successfully.***

Code Example

<?php
	$res = unlink(‘file.txt’);
	if($res){
		echo “File deleted successfully”;
	}
?>