What are function coverage and function overloading in PHP

Function overloading and overwriting (also called rewriting) are OOP (object-oriented) features in PHP. In function overloading, multiple functions can have the same method name but different number or types of parameters. But in case of function overriding, multiple functions will have the same method name and number of parameters.

Function overloading: Function overloading contains the same function name, which performs different tasks depending on the number and type of parameters.

For example, to find the area of ​​some shape given the radius, if the height and width are given, the area of ​​the circle should be returned, then the rectangular area and other areas should be given. Like other OOP languages, function overloading cannot be done through native methods.

In PHP, function overloading is done with the help of the magic method __call(). This function takes a function name and parameters.

Example of function overloading:

<?php 
// 说明:PHP程序说明函数。
// PHP中的重载
//创建一个类型为shape的类
class shape { 
      
   // __call() 是一个魔术方法
   //函数名和参数
    function __call($name_of_function, $arguments) { 
              
        // 它将匹配函数名
        if($name_of_function == &#39;area&#39;) { 
              
            switch (count($arguments)) { 
                      
                // 如果只有一个参数
                //圆的面积
                case 1: 
                    return 3.14 * $arguments[0]; 
                          
                // 如果有两个参数，则面积为矩形;
                case 2: 
                    return $arguments[0]*$arguments[1]; 
            } 
        } 
    } 
} 
      
//声明Shape类型对象
$s = new Shape; 
      
echo($s->area(2)); 
echo "<br>"; 
      
// 调用矩形的area方法
echo ($s->area(4, 2)); 
?>

Output:

6.28
8

Function overriding: Function overriding and other OOPs The programming language is the same. In function overriding, the parent class and child class should have the same function name and number of parameters. It is used to replace the parent method in the child class. The purpose of overriding is to change the behavior of the parent class method. Two methods with the same name and the same parameters are called overrides.

Example of function coverage (rewriting):

<?php
//PHP程序实现
//函数覆盖
//这是父类
class P {

    // 父类函数demo
    function demo() {
        echo "Parent";
    }
}

// 这是子类
class C extends P {

    // 覆盖demo方法
    function demo() {
        echo "<br>Child";
    }
}


$p = new P;

$c= new C;

// 打印parent
$p->demo();

// 打印child
$c->demo();
?>

Output:

Parent
Child

This article is about function coverage and function overloading in PHP Introduction, I hope it will be helpful to friends in need!

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