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This article will introduce header()the concept of the function and its syntax in PHP. It will cover the rules for writing headers in PHP. This approach also applies to Content-Typethe and Content-Dispositionheaders.

location:We will also cover header strings in this article . We will explain the usage and essence of location header in PHP. This article will demonstrate how the location header can send a response code and redirect the browser to another page.

Header()Introduction to functions and their syntax in PHP

header()The function is a built-in PHP function that allows us to send raw HTTP headers to the client. The headers sent are in raw form. We should call header()the function before sending any output. Any form of output, such as HTML tags or output sent by PHP forms, should be discarded before sending the header information. So we can control the information that the server sends to the browser before any output.

header()The syntax of the function is: header(string,replace,http_response_code);. The function accepts three parameters. The first parameter is the header string. There are two types of header strings. The first type is HTTP/a string that starts with . It specifies the HTTP code to be sent to the browser. The second type of header string is location:the header, which redirects the browser to the specified location. The next parameter in the function is replace, which represents a Boolean value. It is an optional parameter that determines whether the header should replace a previous similar header. The third parameter http_response codeis also an optional parameter that is used to force the HTTP response code to a specified value.

For example, create a header()function and use the title string as Content-Type. Content-TypeWrite the value of as application/pdf. Create another header()function again. This time, write the title string as Content-Disposition. Assign the value of the string as attachment. Don't forget to put a semicolon after it. Write another property after the semicolon filenameand provide the file name as download.pdf.

When we run the following script, a download dialog box will appear. It asks you to download a file named download.pdf. pdfThe first header indicates that the file should be pdfin format, and the second header indicates the file's file name and forces the browser to display a dialog box to save the file.

Sample code:

#php 7.x
<?php
header('Content-Type: application/pdf'); 
header('Content-Disposition: attachment; filename="downloaded.pdf"');
?>

header()Using functions and location:title strings in PHP

We can use the redirect header()function with the header string in PHP location:. The header string redirects a web page to a specified location. It is commonly used in web pages to redirect users to a specific page after submitting their input. For example, when a user enters the correct credentials at login time, we can redirect them to the home page using the header location. We can header()specify a boolean value and a response code in the redirect function. However, these parameters are optional. The default boolean value is true, which means it will replace previous similar headers. We can also provide a response code as the third parameter. The default response code is 302. For example, we can write an array to a file and redirect the current page to another page that displays a message that the file has been written. We can file_put_contents()write to a file using the redirect function.

For example, $daycreate an array on the variable. Create keys as weatherand timeand corresponding values ​​as Sunnyand 1:30 pm. Then use file_input_contents()and specify a file file.txtas the first argument. Use print_r()the function as the second argument. Provide the variable $dayand the boolean value trueas print_r()arguments to the function. ifEvaluate the entire expression using the condition. ifUse the function inside the block header(). Within the function, specify the position as message.php. Specify the position using a colon :. Note that there should not be any gap between the locationand colons. Create a PHP file . Display a message in the file stating that the file has been written.:message.php

In the above example, the array is written to the file file.txt. ifThe condition evaluates to true and header()the function redirects the location to message.php. Hence, the output is displayed. We can also see the changed URL in the address bar. If there is another header function below the existing one, the latter header will replace the previous one. This is because in header()the function, replacethe default value of the option is true.

Code example:

#php 7.x
<?php
$day = array (
    'weather' => 'Sunny',
    'time' => '1:30 pm',
);
if(file_put_contents('file.txt', print_r($day, true))){
    header("location: message.php");
}
?>

Output:

The file has been written.