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

In PHP programming we often need to read and write files, and sometimes we need to know the current file pointer position to perform specific processing. PHP provides the ftell() function, which conveniently returns 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 associated with the $handle parameter in the stream. It returns false on error.

Parameter description:

$handle

: file resource handle obtained via functions such as fopen().

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 is:

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 the content is printed. Then ftell() obtains the current pointer offset, stores it in $position, and prints it. 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.

Summary:

The ftell() function is a very useful PHP file‑handling function that easily provides the current file pointer position, allowing developers to perform further processing based on that location. In practice, it can be combined with other file‑operation functions to write more flexible and efficient code.