php - 我可以在 PHP 的函数中使用常量吗？

Question

是否可以在 PHP 函数中使用 PHP 常量？

// in a different file
DEFINE ('HOST', 'hostname');
DEFINE ('USER', 'username');
DEFINE ('PASSWORD', 'password');
DEFINE ('NAME', 'dbname');

// connecting to database
function database()
{
    // using 'global' to define what variables to allow
    global $connection, HOST, USER, PASSWORD, NAME;
    $connection = new mysqli(HOST, USER, PASSWORD, NAME)
        or die ('Sorry, Cannot Connect');
    return $connection;
}

Answer 1

你不需要在函数的 global 中声明它们，PHP 将它们识别为全局变量。

function database()
{
  // using 'global' to define what variables to allow
  global $dbc;
  $connection = new mysqli(HOST, USER, PASSWORD, NAME)
      or die ('Sorry, Cannot Connect');
  return $connection;
}

来自 php.net:

Like superglobals, the scope of a constant is global. You can access constants anywhere in your script without regard to scope. For more information on scope, read the manual section on variable scope.