Mastering PHP’s ftell(): How to Get File Pointer Position with Code Examples

In PHP programming, file read/write operations often require knowing the current file pointer position, which can be obtained using the

ftell()

function.

This article introduces the usage of

ftell()

with code examples.

Function Overview:

ftell(resource $handle): int

The function returns the current position of the file pointer in the byte stream for the handle provided, or false on error.

Parameters:

$handle

: The file resource handle obtained via functions like

fopen()

.

Return Value:

Returns the byte offset of the current file pointer, or false on failure.

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!";
}
?>

Running this code with

example.txt

containing "Hello, World!" produces:

File content: Hello, Wor
File pointer position: 10

The script opens the file with

fopen()

, reads 10 bytes using

fread()

, prints the content, then calls

ftell()

to get the pointer position, prints it, and finally closes the file with

fclose()

.

Note that

ftell()

returns the byte offset; when a file is opened in text mode, characters such as Chinese characters may occupy multiple bytes, so the offset reflects bytes, not characters.

Conclusion

The

ftell()

function is a practical tool in PHP file operations, allowing developers to easily obtain the current file pointer position and combine it with other file functions for flexible processing, thereby improving code efficiency.