header_remove - PHP code example

PHP Function Header_Remove

The php function header_remove is used to remove an HTTP header that has been previously set with the header() function. It's important to understand the syntax and usage of this function in order to avoid common errors such as "Cannot modify header information - header already sent".

The below example sets a header to redirect users to the specified URI. It also uses the header property Content-type to set a file type of application/pdf. This forces the browser to download the page rather than displaying it in the browser's cache. This also sets the Expires header with a date in the past to prevent caching.

Using this function is useful for creating applications that are unable to be cached or whose caching settings are not ideal. This is especially true for applications that use dynamic content such as news sites, social media apps and blogs. It is very easy to use php function header_remove to control this issue.

There are many other functions that you can use to manage the HTTP headers in your application. Some of these include array_replace(), array_replace_recursive(), class_alias(), get_called_class(), gc_collect_cycles(), lcfirst() and forward_static_call(). These functions are very helpful in avoiding errors that can be caused by modifying header information.

The header function is a useful tool to have when working with web servers. It is important to understand how this function works so that you can be aware of any potential issues when developing an application.

header_remove example

// As recommended by RFC 8297, PHP automatically copies headers from previous 103 responses, we need to deal with that if headers changed             if (103 === $statusCode) {
                $previousValues = $this->sentHeaders[$name] ?? null;
                if ($previousValues === $values) {
                    // Header already sent in a previous response, it will be automatically copied in this response by PHP                     continue;
                }

                $replace = 0 === strcasecmp($name, 'Content-Type');

                if (null !== $previousValues && array_diff($previousValues, $values)) {
                    header_remove($name);
                    $previousValues = null;
                }

                $newValues = null === $previousValues ? $values : array_diff($values, $previousValues);
            }

            foreach ($newValues as $value) {
                header($name.': '.$value, $replace, $this->statusCode);
            }

            if ($informationalResponse) {

if (!$this->config->get('cookie_note_mode') || !$this->config->get('show_cookie_note')) {
            return;
        }

        $allowCookie = $this->request->cookies->getInt('allowCookie');

        if ($this->config->get('cookie_note_mode') === CookieRemoveSubscriber::COOKIE_MODE_ALL) {
            if ($allowCookie === 1) {
                return;
            }

            header_remove('Set-Cookie');

            $this->cookieRemoveHandler->removeAllCookies($this->request, $this->response);

            return;
        }

        if ($this->config->get('cookie_note_mode') === CookieRemoveSubscriber::COOKIE_MODE_TECHNICAL) {
            if ($allowCookie === 1) {
                return;
            }

function nocache_headers() {
    if ( headers_sent() ) {
        return;
    }

    $headers = wp_get_nocache_headers();

    unset( $headers['Last-Modified'] );

    header_remove( 'Last-Modified' );

    foreach ( $headers as $name => $field_value ) {
        header( "{$name}: {$field_value}" );
    }
}

/** * Sets the HTTP headers for caching for 10 days with JavaScript content type. * * @since 2.1.0 */

// As recommended by RFC 8297, PHP automatically copies headers from previous 103 responses, we need to deal with that if headers changed             if (103 === $statusCode) {
                $previousValues = $this->sentHeaders[$name] ?? null;
                if ($previousValues === $values) {
                    // Header already sent in a previous response, it will be automatically copied in this response by PHP                     continue;
                }

                $replace = 0 === strcasecmp($name, 'Content-Type');

                if (null !== $previousValues && array_diff($previousValues, $values)) {
                    header_remove($name);
                    $previousValues = null;
                }

                $newValues = null === $previousValues ? $values : array_diff($values, $previousValues);
            }

            foreach ($newValues  as $value) {
                header($name.': '.$value, $replace, $this->statusCode);
            }

            if ($informationalResponse) {

if (11 !== strpos($h, $sessionCookieWithId, 11)) {
                    $otherCookies[] = $h;
                }
            } else {
                $otherCookies[] = $h;
            }
        }
        if (null === $sessionCookie) {
            return null;
        }

        header_remove('Set-Cookie');
        foreach ($otherCookies as $h) {
            header($h, false);
        }

        return $sessionCookie;
    }
}

$headers = apply_filters( 'wp_headers', $headers, $this );

        if ( ! empty( $status ) ) {
            status_header( $status );
        }

        // If Last-Modified is set to false, it should not be sent (no-cache situation).         if ( isset( $headers['Last-Modified'] ) && false === $headers['Last-Modified'] ) {
            unset( $headers['Last-Modified'] );

            if ( ! headers_sent() ) {
                header_remove( 'Last-Modified' );
            }
        }

        if ( ! headers_sent() ) {
            foreach ( (array) $headers as $name => $field_value ) {
                header( "{$name}: {$field_value}" );
            }
        }

        if ( $exit_required ) {
            exit;
        }

    }

    /** * Removes an HTTP header from the current response. * * @since 4.8.0 * * @param string $key Header key. */
    public function remove_header( $key ) {
        header_remove( $key );
    }

    /** * Retrieves the raw request entity (body). * * @since 4.4.0 * * @global string $HTTP_RAW_POST_DATA Raw post data. * * @return string Raw request data. */