Programming Forums > Web Development and Design > PHP

leo1502 · Aug 8th, 2006, 1:44 PM

I'm seeing a lot of the header() function.
Can anyone tell me what exactly are raw-headers and how do they work?
Thanks a lot.

Sane · Aug 8th, 2006, 2:15 PM

When the server returns the page that the client requests, it also attaches along hidden information that the browser uses (but doesn't necessarily let you see).

The header information can be used to tell your browser to use the cached page, it can be used to raise a 404 (missing page), a 505 (server error), it's used to tell the browser what server the site is running on.

It can also be used to differentiate data from html (Content-type: text/html) and an image (Content-type: image/jpeg). Or even trigger file downloads (Content-type: application/x-download).

This is all part of what makes up the Hyper Text Transfer Protocal (HTTP). Basically, it's what helps your browser interpret precisely what the server wants you to see.

With use of the header() function in PHP, you can modify the raw header by simply putting the information in to the funtion call. Without use of the header() function, the default header information is used according to the PHP default settings. So doing something like "header('Content-type: image/jpeg')", will modify the default content-type attribute to the newly specified format.

For further understanding, here's an example of a PHP download script. It has some undeclared variables, but it's simple to work in to something usable.

(Toggle Plain Text)

  $stream = fopen($fname, 'rb');
  $contents = fread($stream, filesize($fname));
  fclose($stream);

  header('Content-Type: application/x-download');
  header('Content-Disposition: attachment; filename="'.$fname.'"');

  echo $contents;

Jimbo · Aug 8th, 2006, 3:49 PM

header() can also be used for silent redirection

 php Syntax (Toggle Plain Text) 
header("Location: 2ndpage.php");
header("Location: 2ndpage.php");

leo1502 · Aug 9th, 2006, 6:40 PM

Thanks a lot guys.

a thing · Aug 9th, 2006, 6:57 PM

Sane: application/x-download is silly. It doesn't tell the browser what the file really is, so it can't decide what to do with it (like open in an external application).

Sane · Aug 10th, 2006, 10:29 AM

I thought if you don't have that, and only have "Content-Disposition" declared, it only works on half of the browsers.

wheedwacker · Sep 30th, 2006, 11:06 PM

http://us3.php.net/manual/en/function.header.php
gives a lot of information on it.

Aug 8th, 2006, 1:44 PM	#1
leo1502 Newbie Join Date: Apr 2006 Posts: 16 Rep Power: 0	header() function, can anyone explain I'm seeing a lot of the header() function. Can anyone tell me what exactly are raw-headers and how do they work? Thanks a lot.

Aug 8th, 2006, 2:15 PM	#2
Sane Banned Join Date: Apr 2005 Location: Waterloo, Ontario Posts: 2,101 Rep Power: 6	When the server returns the page that the client requests, it also attaches along hidden information that the browser uses (but doesn't necessarily let you see). The header information can be used to tell your browser to use the cached page, it can be used to raise a 404 (missing page), a 505 (server error), it's used to tell the browser what server the site is running on. It can also be used to differentiate data from html (Content-type: text/html) and an image (Content-type: image/jpeg). Or even trigger file downloads (Content-type: application/x-download). This is all part of what makes up the Hyper Text Transfer Protocal (HTTP). Basically, it's what helps your browser interpret precisely what the server wants you to see. With use of the header() function in PHP, you can modify the raw header by simply putting the information in to the funtion call. Without use of the header() function, the default header information is used according to the PHP default settings. So doing something like "header('Content-type: image/jpeg')", will modify the default content-type attribute to the newly specified format. For further understanding, here's an example of a PHP download script. It has some undeclared variables, but it's simple to work in to something usable. (Toggle Plain Text) $stream = fopen($fname, 'rb'); $contents = fread($stream, filesize($fname)); fclose($stream); header('Content-Type: application/x-download'); header('Content-Disposition: attachment; filename="'.$fname.'"'); echo $contents; $stream = fopen($fname, 'rb'); $contents = fread($stream, filesize($fname)); fclose($stream); header('Content-Type: application/x-download'); header('Content-Disposition: attachment; filename="'.$fname.'"'); echo $contents; Last edited by Sane; Aug 8th, 2006 at 2:27 PM.

Aug 8th, 2006, 3:49 PM	#3
Jimbo Battle Programmer Join Date: Feb 2006 Location: Bellevue, WA, USA Posts: 770 Rep Power: 3	header() can also be used for silent redirection php Syntax (Toggle Plain Text) header("Location: 2ndpage.php"); header("Location: 2ndpage.php");

Aug 9th, 2006, 6:57 PM	#5
a thing Unverified User Join Date: Aug 2005 Location: none Posts: 146 Rep Power: 0	Sane: application/x-download is silly. It doesn't tell the browser what the file really is, so it can't decide what to do with it (like open in an external application). __________________ Warning: My posts may change (dramatically) within the first 15 minutes they're posted. Got 'Nux?�GNU/Linux and other free software support. It's GNU/Linux, not just Linux.

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Aug 9th, 2006, 6:40 PM	#4
leo1502 Newbie Join Date: Apr 2006 Posts: 16 Rep Power: 0	Thanks a lot guys.

Aug 10th, 2006, 10:29 AM	#6
Sane Banned Join Date: Apr 2005 Location: Waterloo, Ontario Posts: 2,101 Rep Power: 6	I thought if you don't have that, and only have "Content-Disposition" declared, it only works on half of the browsers.

Sep 30th, 2006, 11:06 PM	#7
wheedwacker Newbie Join Date: Sep 2006 Posts: 2 Rep Power: 0	http://us3.php.net/manual/en/function.header.php gives a lot of information on it.

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Programming Forums > Web Development and Design > PHP

header() function, can anyone explain