function http_status_code_string($code, $include_code=false)
{
	// Source: http://en.wikipedia.org/wiki/List_of_HTTP_status_codes

	switch( $code )
	{
		// 1xx Informational
		case 100: $string = 'Continue'; break;
		case 101: $string = 'Switching Protocols'; break;
		case 102: $string = 'Processing'; break; // WebDAV
		case 122: $string = 'Request-URI too long'; break; // Microsoft

		// 2xx Success
		case 200: $string = 'OK'; break;
		case 201: $string = 'Created'; break;
		case 202: $string = 'Accepted'; break;
		case 203: $string = 'Non-Authoritative Information'; break; // HTTP/1.1
		case 204: $string = 'No Content'; break;
		case 205: $string = 'Reset Content'; break;
		case 206: $string = 'Partial Content'; break;
		case 207: $string = 'Multi-Status'; break; // WebDAV

		// 3xx Redirection
		case 300: $string = 'Multiple Choices'; break;
		case 301: $string = 'Moved Permanently'; break;
		case 302: $string = 'Found'; break;
		case 303: $string = 'See Other'; break; //HTTP/1.1
		case 304: $string = 'Not Modified'; break;
		case 305: $string = 'Use Proxy'; break; // HTTP/1.1
		case 306: $string = 'Switch Proxy'; break; // Depreciated
		case 307: $string = 'Temporary Redirect'; break; // HTTP/1.1

		// 4xx Client Error
		case 400: $string = 'Bad Request'; break;
		case 401: $string = 'Unauthorized'; break;
		case 402: $string = 'Payment Required'; break;
		case 403: $string = 'Forbidden'; break;
		case 404: $string = 'Not Found'; break;
		case 405: $string = 'Method Not Allowed'; break;
		case 406: $string = 'Not Acceptable'; break;
		case 407: $string = 'Proxy Authentication Required'; break;
		case 408: $string = 'Request Timeout'; break;
		case 409: $string = 'Conflict'; break;
		case 410: $string = 'Gone'; break;
		case 411: $string = 'Length Required'; break;
		case 412: $string = 'Precondition Failed'; break;
		case 413: $string = 'Request Entity Too Large'; break;
		case 414: $string = 'Request-URI Too Long'; break;
		case 415: $string = 'Unsupported Media Type'; break;
		case 416: $string = 'Requested Range Not Satisfiable'; break;
		case 417: $string = 'Expectation Failed'; break;
		case 422: $string = 'Unprocessable Entity'; break; // WebDAV
		case 423: $string = 'Locked'; break; // WebDAV
		case 424: $string = 'Failed Dependency'; break; // WebDAV
		case 425: $string = 'Unordered Collection'; break; // WebDAV
		case 426: $string = 'Upgrade Required'; break;
		case 449: $string = 'Retry With'; break; // Microsoft
		case 450: $string = 'Blocked'; break; // Microsoft

		// 5xx Server Error
		case 500: $string = 'Internal Server Error'; break;
		case 501: $string = 'Not Implemented'; break;
		case 502: $string = 'Bad Gateway'; break;
		case 503: $string = 'Service Unavailable'; break;
		case 504: $string = 'Gateway Timeout'; break;
		case 505: $string = 'HTTP Version Not Supported'; break;
		case 506: $string = 'Variant Also Negotiates'; break;
		case 507: $string = 'Insufficient Storage'; break; // WebDAV
		case 509: $string = 'Bandwidth Limit Exceeded'; break; // Apache
		case 510: $string = 'Not Extended'; break;

		// Unknown code:
		default: $string = 'Unknown';  break;
	}
	if( $include_code )
		return $code . ' '.$string;
	return $string;
}

HTTP Code values are taken from the Wikipedia entry found here: http://en.wikipedia.org/wiki/List_of_HTTP_status_codes