PHP header() Function

PHP header() sends a raw HTTP header to the browser. Headers are small instructions that go before the actual page content.

Using header() you can redirect a user to another page, change the content type (like JSON), set a status code or force a file download.

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Syntax

header(string $header, bool $replace = true, int $response_code = 0): void

Parameters

Parameter	Description
header	Required. The header string, for example “Location: https://example.com”
replace	Optional. true (default) replaces a previous similar header. false adds a second header of same type
response_code	Optional. Forces the HTTP response code, like 301 or 404

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Common headers

Header	Use
Location: url	Redirect to another URL
Content-Type: application/json	Tell browser that response is JSON
Content-Disposition: attachment; filename=”file.txt”	Download the response as a file
Cache-Control: no-cache	Ask browser not to cache the page

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Examples

Example #1: Redirect to another page

This code sends the user to the Tutorials Class homepage. We call exit after the redirect so rest of the script does not run.

<?php
header("Location: https://tutorialsclass.com/");
exit;
?>

Result: The browser opens https://tutorialsclass.com/ automatically.

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Example #2: Send JSON response

APIs use the Content-Type header, so the client knows it is JSON data.

<?php
header("Content-Type: application/json");

echo json_encode(["name" => "Robin", "city" => "Delhi"]);
?>

Output:

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Example #3: Permanent redirect (301)

Use the third parameter when you move a page forever. Search engines understand 301 as a permanent move.

<?php
header("Location: https://tutorialsclass.com/new-page/", true, 301);
exit;
?>

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Example #4: Download a file

<?php
header("Content-Type: text/plain");
header("Content-Disposition: attachment; filename=\"notes.txt\"");

echo "Hello from Tutorials Class";
?>

Result: The browser downloads a file named notes.txt with the text inside.

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Headers already sent error

This is the most common problem with header(). It happens when the script prints something before header().

<?php
echo "Hello";
header("Location: https://tutorialsclass.com/");
?>

Output:

How to fix it:

• Call header() before any echo, print or HTML.
• Remove blank lines or spaces before the opening <?php tag.
• Save your PHP file as UTF-8 without BOM.
• Use ob_start() at the top if you cannot change the order.

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Summary

• header() sends a raw HTTP header to the browser.
• It must run before any output.
• Call exit after a Location redirect.
• Use the third parameter to set a status code like 301.

• Previous Page
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Exercises & Assignments
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