What functionality does PHP function provide?

PHP functions are predefined blocks of code that perform specific tasks and are used in a wide variety of applications: input validation, data processing, mathematical operations, string manipulation, file manipulation, and database connections. Practical examples include validating email addresses, calculating the average of an array, calculating the area of ​​a rectangle, capitalizing the first letter of a string, reading the contents of a file, and connecting to a database.

PHP functions: uses and practical cases

Introduction to PHP functions

PHP Functions are predefined blocks of code that perform specific tasks. They make code more modular, reusable, and easier to maintain.

Purpose of PHP functions

PHP functions are widely used for:

• Input validation
• Data processing
• Mathematical operations
• String operations
• File operations
• Database connection

Practical cases

1. Input validation

function validate_email($email) {
  return filter_var($email, FILTER_VALIDATE_EMAIL);
}

// 使用例
if (validate_email("user@example.com")) {
  echo "电子邮件地址有效";
} else {
  echo "电子邮件地址无效";
}

2. Data processing

function average($array) {
  return array_sum($array) / count($array);
}

// 使用例
$numbers = [1, 2, 3, 4, 5];
echo average($numbers); // 输出：3

3. Mathematical operations

function calculate_area($length, $width) {
  return $length * $width;
}

// 使用例
echo calculate_area(5, 10); // 输出：50

4. String operation

function capitalize_first_letter($string) {
  return ucfirst($string);
}

// 使用例
echo capitalize_first_letter("hello world"); // 输出：Hello world

5. File operation

function read_file($file_name) {
  return file_get_contents($file_name);
}

// 使用例
$content = read_file("file.txt");
echo $content; // 输出：文件内容

6. Database connection

function connect_to_database() {
  return new PDO("mysql:host=localhost;dbname=mydatabase", "root", "password");
}

// 使用例
$db_connection = connect_to_database();
$query = "SELECT * FROM users";
$result = $db_connection->query($query);

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