February 2013
Intermediate to advanced
538 pages
20h 55m
English
Content preview from Programming PHP, 3rd EditionBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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Setting Response Headers
As we’ve already discussed, the HTTP response that a server
sends back to a client contains headers that identify the type of content
in the body of the response, the server that sent the response, how many
bytes are in the body, when the response was sent, etc. PHP and Apache
normally take care of the headers for you, identifying the document as
HTML, calculating the length of the HTML page, and so on. Most web applications never need to set headers
themselves. However, if you want to send back something that’s not HTML, set the
expiration time for a page, redirect the client’s browser, or generate a
specific HTTP error, you’ll need to use the header() function.
The only catch to setting headers is that you must do so before any
of the body is generated. This means that all calls to header() (or setcookie(), if you’re setting cookies) must
happen at the very top of your file, even before the <html> tag. For example:
<?php header("Content-Type: text/plain"); ?>
Date: today
From: fred
To: barney
Subject: hands off!
My lunchbox is mine and mine alone. Get your own,
you filthy scrounger!Attempting to set headers after the document has started results in this warning:
Warning: Cannot add header information - headers already sentYou can instead use an output buffer; see ob_start(), ob_end_flush(), and related functions for more
information on using output buffers.
Different Content Types
The Content-Type header identifies the type of document being returned. Ordinarily ...
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.