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

In PHP programming, reading and writing files often requires knowing the current file pointer position; the

ftell()

function provides this capability.

This article introduces the usage of

ftell()

with code examples.

Function Overview:

<code>ftell(resource $handle): int</code>

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

Parameter Description:

$handle

: file resource handle obtained via

fopen()

or similar functions.

Return Value:

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

Code Example:

The following example reads the first 10 bytes of a file and obtains the pointer position using

ftell()

:

<code>&lt;?php
$filename = "example.txt";
$handle = fopen($filename, "r");
if ($handle) {
    $content = fread($handle, 10);
    echo "File content: " . $content . "&lt;br/&gt;";
    $position = ftell($handle);
    echo "File pointer position: " . $position;
    fclose($handle);
} else {
    echo "Unable to open file!";
}
?&gt;</code>

Assuming

example.txt

contains "Hello, World!", the output is:

<code>File content: Hello, Wor
File pointer position: 10</code>

The script opens the file with

fopen()

, reads 10 bytes with

fread()

, prints the content, then uses

ftell()

to retrieve and display the pointer position, 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 is calculated in bytes.

Conclusion:

The

ftell()

function is a useful tool in PHP file operations, allowing developers to obtain the current file pointer position and combine it with other file functions to enhance code efficiency.