PHP | ftell( ) Function

The ftell() function in PHP is an inbuilt function which is used to return the current position in an open file. The file is sent as a parameter to the ftell() function and it returns the current file pointer position on success, or FALSE on failure.
Syntax:

ftell( $file )

Parameters Used: The ftell() function in PHP accepts only one parameter $file. It is a mandatory parameter which specifies the file.
Return Value: It returns the current file pointer position on success, or FALSE on failure.
Exceptions: 

1. Some filesystem functions may return unexpected results for files which are larger than 2GB since PHP’s integer type is signed and many platforms use 32bit integers.
2. When opening a file for reading and writing via fopen(‘file’, ‘a+’) the file pointer should be at the end of the file.

Examples: 

Input : $myfile = fopen("gfg.txt", "r");
        echo ftell($myfile);
Output : 0

Input : $myfile = fopen("gfg.txt", "r");
        echo ftell($myfile);
        fseek($myfile, "36");
        echo ftell($myfile);
Output : 0
         36

Below programs illustrate the ftell() function:
Program 1: In the below program the file named gfg.txt contains the following content. 

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php

<?php
// Opening a file in read. mode
$myfile = fopen("gfg.txt", "r");

// displaying the current position of the pointer in the opened file
echo ftell($myfile);

// closing the file
fclose($myfile);
?>

Output:

0

Program 2: In the below program the file named gfg.txt contains the following content. 

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php

<?php
// Opening a file in read. mode
$myfile = fopen("gfg.txt", "r");

// displaying the current position of the pointer in the opened file
echo ftell($myfile);

// changing current position
fseek($myfile, "36");

//displaying current position
echo "<br />" . ftell($myfile);

// closing the file
fclose($myfile);
?>

Output:

0
36

Reference: http://php.net/manual/en/function.ftell.php