AI Overview
To overwrite the text of a file in PHP at a specific byte offset, you can use the fopen(), fseek(), and fwrite() functions.
Here is a step-by-step process:

   Open the file: Use fopen() to open the file in a mode that allows writing (e.g., "r+", "w+", "a+"). The "r+" mode is generally suitable for modifying existing files as it allows both reading and writing without truncating the file.

Code

   <?php
   $file = 'your_file.txt';
   $handle = fopen($file, 'r+');
   if ($handle === false) {
       die("Could not open file for writing.");
   }
   ?>

   Seek to the desired offset: Use fseek() to move the file pointer to the specific byte offset where you want to start overwriting.

Code

   <?php
   $offset = 10; // Example offset in bytes
   if (fseek($handle, $offset) === -1) {
       fclose($handle);
       die("Could not seek to offset.");
   }
   ?>

   Write the new data: Use fwrite() to write the new text starting from the current file pointer position. The fwrite() function will overwrite the existing content at that location.

Code

   <?php
   $newText = 'NEW TEXT'; // The text to be written
   if (fwrite($handle, $newText) === false) {
       fclose($handle);
       die("Could not write to file.");
   }
   ?>

   Close the file: After writing, close the file using fclose() to release the file handle and ensure all changes are saved.

Code

   <?php
   fclose($handle);
   echo "File updated successfully.";
   ?>

Complete Example:
Code

<?php
$file = 'example.txt';
$offset = 5; // Start overwriting at the 5th byte
$newText = 'OVERWRITTEN';

// Create a sample file if it doesn't exist
if (!file_exists($file)) {
   file_put_contents($file, 'Original content here.');
}

$handle = fopen($file, 'r+'); // Open for reading and writing
if ($handle === false) {
   die("Error: Could not open file '{$file}' for writing.");
}

// Move the file pointer to the specified offset
if (fseek($handle, $offset) === -1) {
   fclose($handle);
   die("Error: Could not seek to offset {$offset}.");
}

// Write the new text, overwriting existing content
if (fwrite($handle, $newText) === false) {
   fclose($handle);
   die("Error: Could not write to file '{$file}'.");
}

fclose($handle);
echo "File '{$file}' updated successfully at offset {$offset}.\n";
echo "New content of '{$file}': " . file_get_contents($file);
?>