写入文件php函数

I'm very new to php, I'm trying to create a simple function that will write the name of the person on people.txt file.

I started with the code below.

<?php
session_start();
$counter_name = "people.txt";

if (!file_exists($counter_name)) {
  $f = fopen($counter_name, "w");
  fwrite($f,"0");
  fclose($f);
}

$f = fopen($counter_name,"r");
$person = fread($f, filesize($counter_name));
fclose($f);
$f = fopen($counter_name, "w");
fwrite($f, $person);
fclose($f);

Basically I to give user the website like this: www.mywebsite.com/person.php+personName

In the results, this person name will be added to people.txt file. If a new person will access this page, then the name of the new person will be added to the next line. Something like this:

person1;
person2;
person3;
...

Please some help to figure out the rest of this function.

function appendToFile($stringOrArray, $fileName, $eol = true)
  $fp = fopen('people.txt', 'a');
  $e = $eol ? PHP_EOL : '';
  if(is_string($stringOrArray)){
    fwrite($fp, $stringOrArray.$e); fclose($fp);
    return true;
  }
  elseif(is_array($stringOrArray)){
    foreach($stringOrArray as $v){
      fwrite($fp, $v.$e);
    }
    fclose($fp);
    return true
  }
  else{
    die('$stringOrArray must be a String or Array');
  }
  return false;
}
appendToFile('Single String', 'people.txt');
appendToFile('Another Line', 'people.txt');
appendToFile(array('First Array Element' 'Second Array Element'), 'people.txt');

Note that you don't have to see if the file exists, since it will be created anyways. Also, I would create a class, more like:

class FileHandler{
  private $fn, $fp, $md;
  public function __construct($fileName){
    $this->fn = $fileName;
  }
  public function getFileName(){
    return $thsi->fn;
  }
  public function setMode($mode){
    $this->md = $mode; $this->fp = fopen($this->fn, $mode);
    return $this;
  }
  public function getFilePointer(){
    return $this->fp;
  }
  public function getMode(){
    return $this->md;
  }
  private function fc(){
    fclose($this->fp);
  }
  public function exec($maybe, $eol = true){
    $fp = $this->fp;
    $e = $eol ? PHP_EOL : '';
    switch($this->md){
      case 'r':
        break;
      case 'r+':
        break;
      case 'w':
        break;
      case 'w+':
        break;
      case 'a':
        if(is_string($maybe)){
          fwrite($fp, $maybe.$e); $this->fc();
          return true;
        }
        elseif(is_array($maybe)){
          foreach($maybe as $v){
            fwrite($fp, $v.$e);
          }
          $this->fc();
          return true;
        }
        else{
          die('$maybe must be a String or Array with mode \'a\'');
        }
        break;
      case 'a+':
        break;
      case 'x':
        break;
      case 'x+':
        break;
      case 'c':
        break;
      case 'c+':
        break;
      default:
        // maybe you want a mode if none is selected
        break;
    }
    return false;
  }
}
$fh = new FileHandler('people.txt');
$fh->setMode('a')->exec(array('value 0', 'value 1', 'value 2'));

Of course, you have to add to the modes and write a bunch of other code. Have fun!