<?php
class FileOperator
{
  var $lines;

  function FileOperator( $filename, $numLines )
  {
    $this->lines = array();
    $this->readLines( $filename, $numLines );
  }

  private function readLines ( $filename, $numLines )
  {
    $i = 0;
    if( !file_exists( $filename ) || !is_readable( $filename ) ) {
      die( "Error reading file." );
    }
    $fp = fopen( $filename , "r" );
    while( $i < $numLines )
    {
      if( $fp !== false ) {
        $this->lines[] = fgets($fp);
        $i++;
      }
      else {
         die( "Error reading file." );
      }
    }
    fclose( $fp );
  }

  public function getLines( $concat = false, $concatChar = "\n" )
  {
    if( !is_array( $this->lines )) {
       die( "use FileOperator::readLines() first." );
    }
    if( $concat !== false )
    {
      return implode( $concatChar, $this->lines);
    }
    else {
      return $this->lines;
    }
  }
}

$tiedosto = 'test.txt';
$riveja = 5;

$File = new FileOperator( $tiedosto, $riveja );
echo $File->getLines( true );