Read a range of file lines in ColdFusion

filereadlines.cfc

/**
*
* Based on a UDF by Raymond Camden (https://cflib.org/udf/FileRead)
*
* @hint Read a range of lines from a file
* @filepath path to the file being read
* @start number of the first line to read
* @end number of the last line to read
*/
public string function fileReadLines( required string filepath, required numeric start, required numeric end ) {

  if( !fileExists(filepath) ){
    return "";
  }

  var fileLines = '';
  var fileObject = fileOpen(filepath);
  var done = false;
  var lineNumber = 0;

  try {
    while( !done ) {
      lineNumber++;
      var line = fileReadLine(fileObject);
      if( lineNumber >= start ){
        fileLines &= line;
        if( lineNumber < end ){
          fileLines &= Chr(13) & Chr(10);
        }
      }
      if( lineNumber == end ){
        done = true;
      }
    }
  } catch( any e ) {
      rethrow;
  } finally {
      fileClose( fileObject );
  }

  return fileLines;
}