php
if (isset($_server['server_port'])) { $port = ':' . $_server['server_port']; if ((':80' == $port && 'http://' == $protocol) || (':443' == $port && ' https://' == $protocol)) { $port = ''; } }
其中
if ((':80' == $port && 'http://' == $protocol) || (':443' == $port && 'https://' == $protocol)) { $port = ''; }
这段代码的意思作用是什么？ 如果条件成立，为什么要把$port 设置为空？
整个函数的代码：
function get_domain() { /* 协议 */ $protocol = $this->http(); /* 域名或ip地址 */ if (isset($_server['http_x_forwarded_host'])) { $host = $_server['http_x_forwarded_host']; } elseif (isset($_server['http_host'])) { $host = $_server['http_host']; } else { /* 端口 */ if (isset($_server['server_port'])) { $port = ':' . $_server['server_port']; if ((':80' == $port && 'http://' == $protocol) || (':443' == $port && 'https://' == $protocol)) { $port = ''; } } else { $port = ''; } if (isset($_server['server_name'])) { $host = $_server['server_name'] . $port; } elseif (isset($_server['server_addr'])) { $host = $_server['server_addr'] . $port; } } return $protocol . $host; }