Class as a Set of Methods in OOP in PHP

Sometimes classes are used to group methods of similar topics. In this case, as a rule, only one object of this class is created and its methods are used many times in various situations.

Let's look at an example. Let's create a class that will manipulate arrays of numbers:

php<?php
  class ArrHelper {
    
  }
?>

Each method of this class will take an array as a parameter and perform a specified operation on it. Let's say, for example, we have the following methods:

php<?php
  class ArrHelper {
    public function getSum($arr) {
      // sum of elements
    }
    
    public function getAvg($arr) {
      // arithmetic mean
    }
  }
?>

Let's write the implementation of these methods:

php<?php
  class ArrHelper {
    public function getSum($arr) {
      $res = 0;
      
      foreach ($arr as $num) {
        $res += $num;
      }
      
      return $res;
    }
    
    public function getAvg($arr) {
      $len = count($arr);
      
      if ($len > 0) {
        $sum = $this->getSum($arr);
        return $sum / $len;
      } else {
        return 0;
      }
    }
  }
?>

Let's see how we will use these methods. Let's create an object of our class:

php<?php
  $arrHelper = new ArrHelper();
?>

Let's find the sum of numbers of various arrays using our object:

php<?php
  $sum1 = $arrHelper->getSum([1, 2, 3]);
  var_dump($sum1);
  
  $sum2 = $arrHelper->getSum([3, 4, 5]);
  var_dump($sum2);
?>