php回来HTTP状态码

面试时很多人问我这个，记录一下???200是ok,??404表示页面未找到.
HTTP协议状态码,调用函数时候只需要将$num赋予一个下表中的已知值就直接会返回状态了。
<?PHP?
/**?
*?HTTP?Protocol?defined?status?codes
*?HTTP协议状态码,调用函数时候只需要将$num赋予一个下表中的已知值就直接会返回状态了。
*?@param?int?$num
*/?
function?https($num)?{?
$http?=?array?(?
100?=>?"HTTP/1.1?100?Continue",?
101?=>?"HTTP/1.1?101?Switching?Protocols",?
200?=>?"HTTP/1.1?200?OK",?
201?=>?"HTTP/1.1?201?Created",?
202?=>?"HTTP/1.1?202?Accepted",?
203?=>?"HTTP/1.1?203?Non-Authoritative?Information",?
204?=>?"HTTP/1.1?204?No?Content",?
205?=>?"HTTP/1.1?205?Reset?Content",?
206?=>?"HTTP/1.1?206?Partial?Content",?
300?=>?"HTTP/1.1?300?Multiple?Choices",?
301?=>?"HTTP/1.1?301?Moved?Permanently",?
302?=>?"HTTP/1.1?302?Found",?
303?=>?"HTTP/1.1?303?See?Other",?
304?=>?"HTTP/1.1?304?Not?Modified",?
305?=>?"HTTP/1.1?305?Use?Proxy",?
307?=>?"HTTP/1.1?307?Temporary?Redirect",?
400?=>?"HTTP/1.1?400?Bad?Request",?
401?=>?"HTTP/1.1?401?Unauthorized",?
402?=>?"HTTP/1.1?402?Payment?Required",?
403?=>?"HTTP/1.1?403?Forbidden",?
404?=>?"HTTP/1.1?404?Not?Found",?
405?=>?"HTTP/1.1?405?Method?Not?Allowed",?
406?=>?"HTTP/1.1?406?Not?Acceptable",?
407?=>?"HTTP/1.1?407?Proxy?Authentication?Required",?
408?=>?"HTTP/1.1?408?Request?Time-out",?
409?=>?"HTTP/1.1?409?Conflict",?
410?=>?"HTTP/1.1?410?Gone",?
411?=>?"HTTP/1.1?411?Length?Required",?
412?=>?"HTTP/1.1?412?Precondition?Failed",?
413?=>?"HTTP/1.1?413?Request?Entity?Too?Large",?
414?=>?"HTTP/1.1?414?Request-URI?Too?Large",?
415?=>?"HTTP/1.1?415?Unsupported?Media?Type",?
416?=>?"HTTP/1.1?416?Requested?range?not?satisfiable",?
417?=>?"HTTP/1.1?417?Expectation?Failed",?
500?=>?"HTTP/1.1?500?Internal?Server?Error",?
501?=>?"HTTP/1.1?501?Not?Implemented",?
502?=>?"HTTP/1.1?502?Bad?Gateway",?
503?=>?"HTTP/1.1?503?Service?Unavailable",?
504?=>?"HTTP/1.1?504?Gateway?Time-out"??
);?
header($http[$num]);?
}?
?>

@header('HTTP/1.0?404?Not?Found');