What are the applications of PHP functions in web development?

PHP functions are widely used in web development for data processing, authentication, database operations, form processing, page display, file processing and error handling. For example, it can be used to get request parameters, handle form input, interact with the database, upload files, and catch exceptions.

Use of PHP Functions in Web Development

PHP functions are reusable chunks of code that perform specific tasks. In web development, PHP functions are widely used in the following applications:

1. Data processing

// 获取请求参数值
$name = $_POST['name'];

// 将字符串转换为大写
$name_upper = strtoupper($name);

2. Authentication and authorization

// 创建用户哈希密码
$password = password_hash('password', PASSWORD_BCRYPT);

// 验证用户登录
if (password_verify('password', $password)) {
  // 登录成功
}

3. Database operation

// 连接到数据库
$conn = mysqli_connect('localhost', 'username', 'password', 'database');

// 执行查询
$result = mysqli_query($conn, 'SELECT * FROM users');

// 处理结果
while ($row = mysqli_fetch_assoc($result)) {
  echo $row['name'];
}

4. Form processing

// 验证表单输入
if (!empty($_POST['email']) && filter_var($_POST['email'], FILTER_VALIDATE_EMAIL)) {
  // 表单有效
}

5. Page display

// 加载视图文件
include('header.php');
include('content.php');
include('footer.php');

6. File processing

// 上传文件
if (move_uploaded_file($_FILES['file']['tmp_name'], 'uploads/file.txt')) {
  // 上传成功
}

// 读取文件
$contents = file_get_contents('uploads/file.txt');

7. Error handling

// 捕捉异常
try {
  // 代码
} catch (Exception $e) {
  // 处理异常
}

Practical case: User registration form

// 创建用户
function create_user($name, $email, $password) {
  // 验证输入和密码哈希
  // ...

  // 连接到数据库并插入用户
  // ...

  // 发送激活电子邮件
  // ...
}

// 获取表单数据
$name = $_POST['name'];
$email = $_POST['email'];
$password = $_POST['password'];

// 创建用户
create_user($name, $email, $password);

// 重定向到成功页面
header('Location: success.php');

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