What resources are available to help me learn about PHP functions?

PHP functions are predefined blocks of code that perform specific tasks, simplifying development. They follow a specific syntax, including function name, parameters, and function body, and can be enhanced with type annotations. Practical examples include calculating sums and filtering HTML tags in text. Additional resources are available to help you learn more about PHP functions.

Detailed explanation of PHP functions: from getting started to practice

PHP functions are predefined blocks of code that can be used to perform specific tasks, thereby simplifying the development process. This article will introduce PHP functions in detail, from introductory concepts to practical applications based on real cases.

Function syntax

PHP functions follow the following syntax:

function function_name(argument1, argument2, ..., argumentN) {
    // 函数体
    return (optional);
}

Among them:

• ##function_name: function name, required Begins with a letter or underscore and must not contain any symbols.
• argument1: Parameters required by the function without type declaration.
• Function body: The code block to be executed.
• return (optional): The optional return statement is used to return the function result.

Type annotations

PHP 7 and above support type annotations to improve code readability and prevent errors:

function sum(int $a, int $b): int {
    return $a + $b;
}

Practical case 1: Calculate the sum

The following example demonstrates a PHP function to calculate the sum of two numbers:

<?php
function sum(int $a, int $b): int {
    return $a + $b;
}

$result = sum(5, 10); // 调用函数
echo $result; // 输出：15

Practical Case 2: Data Filtering

The following function is used to filter HTML and JavaScript tags:

<?php
function filter(string $text): string {
    return strip_tags($text);
}

$filteredText = filter("<p>Hello, world</p>"); // 调用函数
echo $filteredText; // 输出：Hello, world

Resources

The following resources can help you learn more about PHP functions:

PHP Function Manual: https://www.php.net/ manual/zh/functions.index.php
• W3Schools PHP function tutorial: https://www.w3schools.com/php/php_functions.asp
• Stack Overflow PHP function tag: https:/ /stackoverflow.com/questions/tagged/php-functions

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