How to create a PHP function library and use it?

To create a PHP function library, create a new file containing the function definition and use require_once to include the function library into the main script. For example, a math library can define sum and product functions and then use them in a script as follows: 1. Define the library; 2. Include the library into the script; 3. Call the library functions.

How to create a PHP function library and use it

Create a function library

Create a new PHP file (e.g. functions.php):

<?php

// 定义一个问候函数
function greet($name) {
    echo "Hello, $name!";
}
?>

Use the function library

Include the function library into your PHP script:

<?php

// 包含函数库
require_once 'functions.php';

// 调用问候函数
greet('John Doe');
?>

Practical case: Math function library

Create a math function library (math.php):

<?php

// 定义一个求和函数
function sum($a, $b) {
    return $a + $b;
}

// 定义一个求乘积函数
function multiply($a, $b) {
    return $a * $b;
}
?>

in your PHP script Math function library used in:

<?php

// 包含函数库
require_once 'math.php';

// 调用求和和求乘积函数
$sum = sum(5, 10);
$product = multiply(2, 3);

echo "求和：$sum" . PHP_EOL;
echo "求乘积：$product" . PHP_EOL;
?>

Output:

求和：15
求乘积：6

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