Using PHP ftell() to Retrieve the Current File Pointer Position

In PHP programming, file read/write operations are common, and sometimes you need to know the current position of the file pointer to perform specific processing. PHP provides the ftell() function to conveniently obtain the current file pointer location.

This article introduces the usage of the ftell() function and includes several code examples.

Function Overview: ftell(resource $handle): int The function returns the current byte offset of the file stream identified by the $handle parameter. It returns false on error.

Parameters

$handle

: The file resource handle obtained via fopen() or similar functions.

Return Value

The function returns the byte offset of the current file pointer, or false if an error occurs.

Code Example

The following example uses ftell() to read the first 10 bytes of a file and obtain the pointer position:

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

if ($handle) {
    $content = fread($handle, 10);
    echo "File content: " . $content . "<br/>";

    $position = ftell($handle);
    echo "File pointer position: $position";

    fclose($handle);
} else {
    echo "Unable to open file!";
}
?>

Assuming example.txt contains "Hello, World!", the output will be:

File content: Hello, Wor
File pointer position: 10

In the code, fopen() opens the file in read‑only mode, fread() reads the first 10 bytes into $content, and ftell() retrieves the current pointer offset, storing it in $position. Finally, fclose() closes the file.

Note that ftell() returns the byte offset of the file pointer. When a file is opened in text mode, characters such as Chinese characters may occupy multiple bytes, so the offset is calculated in bytes, not characters.

Summary

The ftell() function is a very useful tool in PHP file operations. It allows developers to obtain the current file pointer position easily, enabling further processing based on that position. In practice, you can combine ftell() with other file‑handling functions to create flexible and efficient file‑processing logic.