How to integrate custom functions into PHP code?

In PHP, you can integrate a custom function in three steps: Create a function Load a function Call a function This can be applied to a real case in the following ways: Create a custom function that calculates the area of ​​a rectangle Load the function call in code Function multiple times to calculate the area of ​​different rectangles

How to integrate a custom function into PHP code?

In PHP, custom functions allow you to create reusable modules of code that perform specific tasks throughout an application or project. This improves code readability, maintainability, and flexibility.

Steps:

1. Create function:

   function my_custom_function($a, $b = 2) {
       return $a * $b;
   }

2. Load function:

   If you define your custom function in a separate file, you need to include the file into your current script using the include or require statement:

   require 'custom_functions.php';

3. Call the function:

   Once the function is loaded, you can use it like any PHP function:

   $result = my_custom_function(5); // 结果为 10

Practical case:

Suppose we need to create a small program to calculate the area of ​​a rectangle. We can use a custom function to calculate the area and call the function as many times as needed:

// 矩形面积函数
function rectangle_area($length, $width) {
    return $length * $width;
}

// 输入矩形尺寸
$length = 10;
$width = 5;

// 计算并显示面积
$area = rectangle_area($length, $width);
echo "矩形的面积：$area 平方单位";

Output:

矩形的面积：50 平方单位

Notes:

• The function name should Be unique and start with a lowercase letter, and avoid special characters.
• Parameters should be passed by value, which means that any changes to the parameters will not affect the original value of the calling function.
• You can use the global keyword to access global variables inside a function.
• You can use the static keyword in a function declaration to retain the value of a variable even after the function is executed.

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