phpfunction address$economize$market$distinguish$detailed $address = $economize$market$distinguish$detailed; return $address;echo addresshunanchangshachangshaxiansijixingcheng;这个代码可以怎么改

加上单引号或双引号，将参数变为字符串形式，避免出现未定义常量的错误。

在函数调用时将参数用引号包裹起来，如下所示：

echo address('hunan','changsha','changshaxian','sijixingcheng');

可以添加参数类型声明，增强代码可读性和安全性，如下所示：

function address(string $economize, string $market, string $distinguish, string $detailed): string { $address = $economize . $market . $distinguish . $detailed; return $address; }

echo address('hunan', 'changsha', 'changshaxian', 'sijixingcheng');

可以使用默认参数，使函数调用更加简洁，如下所示：

function address(string $economize = '', string $market = '', string $distinguish = '', string $detailed = ''): string { $address = $economize . $market . $distinguish . $detailed; return $address; }

echo address('hunan', 'changsha', 'changshaxian', 'sijixingcheng');

// 或者

echo address(detailed: 'sijixingcheng');