Header that does not want to work [duplicated]

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Header that does not want to work [duplicated]

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#1 by (2 votes)

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I want to redirect to a web page with header in php but it throws me an error that says something like:

PHP Warning:  Cannot modify header information - headers already sent by (output started at /home/sitio/public_html/includeses/analyticstracking.php:1)

and then mention the line number where I have the header defined

$variableApasar = 200;
header('Location: pagina.php?var=' . base64_encode($variableApasar));

PHP what's wrong with you?

php

asked by MNibor 18.11.2017 в 17:19

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1 answer

Show notifications counter in BottomNavigation database.yml rails 5

score 2 · Accepted Answer

PHP functions that send or modify HTTP headers must be executed before the requested page has been sent to the user. Otherwise, the following error will occur:

Warning: Cannot modify header information - headers already sent
(output started at file:line)

The PHP functions that modify the HTTP headers are the following:

header() / header_remove()
session_start() / session_regenerate_id()
setcookie() / setrawcookie()

And the ways to start sending content to the user before these functions are executed can be intentional or unintentional:

Intentional:

Show information with print or echo
Dump the content of variables with var_dump()
Use any of these functions: printf(), trigger_error(), vprintf(), ob_flush(), readfile() o passthru() .
Add HTML code before the%% open% tag

Unintentional:

Add some blank space before <?php or after <?php
The BOM (Byte Order Mark) of UTF-8
Error messages or notices produced previously