Classification and application scenarios of PHP functions

PHP functions can be classified by purpose: core functions perform basic tasks; user-defined functions extend functions; extension functions add task-specific functions. In actual combat, PHP functions can be used to efficiently process data, such as obtaining user names, finding the maximum age, grouping users by city, etc.

Classification and application scenarios of PHP functions

PHP functions are predefined blocks in code that contain reusable functionality. They are categorized by their purpose and functionality, providing developers with an extensive library of features.

1. Core functions

Core functions are basic functions provided in PHP and are used to perform common tasks, such as:

• String operations: strlen(), str_replace(), substr()
• Array operations: array_merge(), array_filter(), array_keys()
• ##Number operations: round(), abs(), max()

## 2. User-defined functions

User-defined functions allow developers to create their own functions and extend the functionality of PHP. They can be used to:

Encapsulate repetitive tasks

• Organize code
• Improve modularity and reusability
• To create A user-defined function can use the

function

keyword, for example: <div class="code" style="position:relative; padding:0px; margin:0px;"><pre class='brush:php;toolbar:false;'>function greet($name) { echo &quot;Hello, $name!&quot;; }</pre><div class="contentsignin">Copy after login</div></div>

3. Extension function

The extension function is provided by a third-party library. Add extra functionality to PHP. They are typically used to handle specific tasks, such as:

Database access:
• mysqli_connect(), PDO::query()
Image processing:
• imagecreate(), imagesave()
Network communication:
• curl_init(), file_get_contents()
##Practical case:

Suppose we have an array $data

stores user details including name, age and city. We can use PHP functions to access and process this information simply and efficiently:

// 获取所有用户姓名
$names = array_column($data, 'name');

// 查找年龄最大的用户
$max_age = max(array_column($data, 'age'));

// 分组用户按城市
$users_by_city = array_reduce($data, function($acc, $item) {
  $acc[$item['city']][] = $item;
  return $acc;
}, []);

By understanding the classification and application scenarios of PHP functions, developers can effectively use functions to speed up development, improve code maintainability and customize PHP behavior .

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