PHP 函数如何返回特定的值

return value;

function get_greeting() {
  return "Hello, world!";
}

$greeting = get_greeting();
echo $greeting; // 输出 "Hello, world!"

function calculate_total($amount, $tax_rate) {
  return $amount + ($amount * $tax_rate);
}

$total = calculate_total(100, 0.1);
echo $total; // 输出 110

function get_user_data($id) {
  // 查询数据库并检索数据
  $data = [
    'name' => 'John Doe',
    'email' => 'john.doe@example.com',
    'age' => 30
  ];

  return $data;
}

$user_data = get_user_data(1);
echo $user_data['name']; // 输出 "John Doe"

function get_student_info($id) {
  // 查询数据库并检索数据
  $info = [
    'name' => 'Jane Doe',
    'major' => 'Computer Science',
    'gpa' => 3.8
  ];

  return $info;
}

$student_info = get_student_info(2);
echo $student_info['name']; // 输出 "Jane Doe"
echo $student_info['major']; // 输出 "Computer Science"

function &get_account_balance() {
  static $balance = 1000;
  return $balance;
}

$balance =& get_account_balance();
$balance += 100;

echo $balance; // 输出 1100