PHP header()
header() function sends a raw HTTP header. header() must be called before
any output of the web page. To other words, header() must be used before the <html> tag.
void header(str string [, bool replace = true, int http_response_code])
There may be several HTTP headers of the same type in a web page. By default, the second HTTP header will replace the first. But if the replace parameter is
false, then all HTTP headers will be kept.
<?PHP
header("HTTP/1.0 404 Not Found");
header("HTTP/1.0 301 Moved Permanently");
header("HTTP/1.0 408 Request Time-out");
?>
header() is usually used for redirect a web page. e.g. following code will redirect to the "index.php" page,
no more content after header() will be showed.
<?PHP
header("LOCATION: index.php");
header('cache-Control: no-store, no-cache, must-revalidate');
header('Cache-Control: post-check=0, pre-check=0',false);
?>
You may set up a specific wait time before the redirection. During the wait, content after header() will be showed.
<?PHP
header("refresh:4; url=index.php");
echo "Please wait, you will be redirect to a new page ...\n";
...
?>
To use variables in the redirection:
<?PHP
$url="index.php";
header("LOCATION: http://www.endmemo.com/$url");
?>
If you have "&" and variables in the redirection, the variables should be concatenated with the url string to avoid confusion:
<?PHP
$p1="a";
$p2="b";
header('LOCATION: xxx.php?p1=".$p1."&p2=".$p2');
?>
header() can be used to forbidden using cache or proxy for the web page. This is important for some web pages that
update frequently.
<?PHP
header('cache-Control: no-store, no-cache, must-revalidate');
header('Cache-Control: post-check=0, pre-check=0',false);
header('Pragma: no-cache');
?>
header() can be used to download file. The following code will download current page.
<?PHP
header("Content-Type:application/octet-stream");
header("Content-Disposition: attachment;");
header("Accept-ranges: bytes");
?>
For more information, visit HTTP Headers.
