Tutorials References Exercises Videos Menu
Create Website Get Certified Upgrade

PHP Tutorial

PHP HOME PHP Intro PHP Install PHP Syntax PHP Comments PHP Variables PHP Echo / Print PHP Data Types PHP Strings PHP Numbers PHP Math PHP Constants PHP Operators PHP If...Else...Elseif PHP Switch PHP Loops PHP Functions PHP Arrays PHP Superglobals PHP RegEx

PHP Forms

PHP Form Handling PHP Form Validation PHP Form Required PHP Form URL/E-mail PHP Form Complete

PHP Advanced

PHP Date and Time PHP Include PHP File Handling PHP File Open/Read PHP File Create/Write PHP File Upload PHP Cookies PHP Sessions PHP Filters PHP Filters Advanced PHP Callback Functions PHP JSON PHP Exceptions

PHP OOP

PHP What is OOP PHP Classes/Objects PHP Constructor PHP Destructor PHP Access Modifiers PHP Inheritance PHP Constants PHP Abstract Classes PHP Interfaces PHP Traits PHP Static Methods PHP Static Properties PHP Namespaces PHP Iterables

MySQL Database

MySQL Database MySQL Connect MySQL Create DB MySQL Create Table MySQL Insert Data MySQL Get Last ID MySQL Insert Multiple MySQL Prepared MySQL Select Data MySQL Where MySQL Order By MySQL Delete Data MySQL Update Data MySQL Limit Data

PHP XML

PHP XML Parsers PHP SimpleXML Parser PHP SimpleXML - Get PHP XML Expat PHP XML DOM

PHP - AJAX

AJAX Intro AJAX PHP AJAX Database AJAX XML AJAX Live Search AJAX Poll

PHP Examples

PHP Examples PHP Compiler PHP Quiz PHP Exercises PHP Certificate

PHP Reference

PHP Overview PHP Array PHP Calendar PHP Date PHP Directory PHP Error PHP Exception PHP Filesystem PHP Filter PHP FTP PHP JSON PHP Keywords PHP Libxml PHP Mail PHP Math PHP Misc PHP MySQLi PHP Network PHP Output Control PHP RegEx PHP SimpleXML PHP Stream PHP String PHP Variable Handling PHP XML Parser PHP Zip PHP Timezones

PHP header() Function

❮ PHP Network Reference

Example

Send three HTTP headers to prevent page caching:

<?php
// Date in the past
header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");
header("Cache-Control: no-cache");
header("Pragma: no-cache");
?>

<html>
<body>
...
...

Note: There are options that users may set to change the browser's default caching settings. By sending the headers above, you will override any of those settings and force the browser to not cache!


Definition and Usage

The header() function sends a raw HTTP header to a client.

It is important to notice that the header() function must be called before any actual output is sent!

Syntax

header(header, replace, http_response_code)

Parameter Values

Parameter Description
header Required. Specifies the header string to send
replace Optional. Indicates whether the header should replace a previous similar header or add a new header of the same type. Default is TRUE (will replace). FALSE allows multiple headers of the same type
http_response_code Optional. Forces the HTTP response code to the specified value


Technical Details

Return Value: Nothing
PHP Version: 4.0+
PHP Changelog: PHP 5.1.2: Now prevents that more than one header to be sent at once. This is a protection against header injection attacks

More Examples

Example

Let the user be prompted to save a generated PDF file (Content-Disposition header is used to supply a recommended filename and force the browser to display the save dialog box):

<?php
header("Content-type:application/pdf");

// It will be called downloaded.pdf
header("Content-Disposition:attachment;filename='downloaded.pdf'");

// The PDF source is in original.pdf
readfile("original.pdf");
?>

<html>
<body>

...
...


❮ PHP Network Reference