In what scenarios does using ftell() or rewind() functions become necessary when working with file pointers in PHP?

When working with file pointers in PHP, using ftell() becomes necessary when you need to determine the current position of the file pointer within a file. This can be useful for tasks such as bookmarking the current position for later use or for calculating the size of a file. Similarly, the rewind() function is necessary when you need to reset the file pointer to the beginning of a file, allowing you to re-read the contents or perform operations from the start.

$file = fopen("example.txt", "r");

// Get the current position of the file pointer
$position = ftell($file);

// Reset the file pointer to the beginning of the file
rewind($file);

// Perform operations from the beginning of the file

fclose($file);