PHP Tutorials - Herong's Tutorial Examples - Version 4.20, by Dr. Herong Yang
header() - Inserting a Raw Header Lines
This section describes how to use the header() function to insert a raw HTTP response header line to reset the status line, replace an existing header line, or add a new header line.
When a PHP page is requested, the PHP engine will add some basic header lines in the HTTP response. But if you want to add new header lines or change those inserted by the PHP engine, you can use the header() function. Here are some rules on how to use the header() function:
1. The syntax of header() is:
void header(string $line, bool $replace, int $code)
2. $line specifies a complete header line string like "Content-Type: text/html".
3. $replace specifies a Boolean value controlling whether to replace a previously defined header line of the same identifier or not. If $replace = TRUE, the specified header line will replace any existing header lines with the same identifier. If $replace = FALSE, the specified header line will not replace any existing header lines with the same identifier. If $replace is not provided, PHP will assume $replace = TRUE.
4. $code specifies an integer to be used as the HTTP response status code. If $code is not provided, the PHP engine will decide the status code.
5. header() must be called before any output to the entity body, if the output buffering is turned off.
6. If header() is called to set "Location" header line, the status line will be set to "HTTP/1.0 302".
7. When header() is called multiple times, the status line will be always generated first. Other header lines will be generated in same order as their calling statements.
Here a sample PHP script code segment that generates some header lines using the header() function:
header("HTTP/1.1 200 OK"); // Reset the status line header("Cache-Control: no-cache, must-revalidate"); header("Expires: Mon, 26 Jul 2017 05:00:00 GMT"); // Past time ok header("Content-Type: text/html; charset=utf-8"); header("Content-Length: 9490"); header("My-Header: SID=909494909", FALSE); // Allow duplicates header("My-Header: UID=Herong", FALSE); // Allow duplicates
Last update: 2019.
Table of Contents
Introduction and Installation of PHP 7.3
PHP Data Types and Data Literals
Variables, References, and Constants
Expressions, Operations and Type Conversions
Conditional Statements - "if" and "switch"
Loop Statements - "while", "for", and "do ... while"
Function Declaration, Arguments, and Return Values
Introduction of Class and Object
Integrating PHP with Apache Web Server
Retrieving Information from HTTP Requests
Creating and Managing Sessions in PHP Scripts
Sending and Receiving Cookies in PHP Scripts
►Controlling HTTP Response Header Lines in PHP Scripts
►header() - Inserting a Raw Header Lines
HttpRequestGet.php - Viewing Header Lines
Response Header Lines of Static Files
HttpHeaderLines.php - Examples of Inserting Header Lines
Location: - Forcing the Browser to Redirect to Another URL
Content-Type: - Generating Non-HTML Response Body
Content-Disposition: - Sending Files for Downloading
MySQL Server Connection and Access Functions
Functions to Manage Directories, Files and Images
SOAP Extension Function and Calling Web Services
SOAP Server Functions and Examples
Localization Overview of Web Applications
Using Non-ASCII Characters in HTML Documents
Using Non-ASCII Characters as PHP Script String Literals
Receiving Non-ASCII Characters from Input Forms
"mbstring" Extension and Non-ASCII Encoding Management
Managing Non-ASCII Character Strings with MySQL Servers