Delete Line From File

Delete Line From File

Here we show how to take a file and a line number and delete that line from the file


<?php
###########################################################################
###                                                                     ###
### This function takes two arguements, $fileName and $lineNum          ###
### The example here shows how to delete line number 14 from the file   ###
### myfile.txt                                                          ###
### Example:                                                            ###
###                                                                     ###
### $fileName = "myfile.txt";                                           ###
### $lineNum = 14                                                       ###
### delLineFromFile($fileName, $lineNum);                               ###
### Author Kevin Waterson kevin@phpro.org                               ###
###                                                                     ###
###########################################################################
// the file name, this can be a path also, like /path/to/myfile.txt$fileName = "myfile.txt";
// the line to delete$lineNum = 87;
delLineFromFile($fileName, $lineNum);


function delLineFromFile($fileName, $lineNum){// check the file exists 
  if(!is_writable($fileName))
    {
    // print an error
    print "The file $fileName is not writable";
    // exit the function
    exit;
    }
  else
      {
    // read the file into an array    
    $arr = file($fileName);
    }

  // the line to delete is the line number minus 1, because arrays begin at zero
  $lineToDelete = $lineNum-1;
 
  // check if the line to delete is greater than the length of the file
  if($lineToDelete > sizeof($arr))
    {
      // print an error
    print "You have chosen a line number, <b>[$lineNum]</b>,  higher than the length of the file.";
    // exit the function
    exit;
    }

  //remove the line
  unset($arr["$lineToDelete"]);

  // open the file for reading
  if (!$fp = fopen($fileName, 'w+'))
    {
    // print an error
        print "Cannot open file ($fileName)";
      // exit the function
        exit;
        }
  
  // if $fp is valid
  if($fp)
    {
        // write the array to the file
        foreach($arr as $line) { fwrite($fp,$line); }

        // close the file
        fclose($fp);
        }

echo "done";
}
?>