headers_sent

(PHP 4, PHP 5)

headers_sent — Checks if or where headers have been sent

설명

bool headers_sent ([ string &$file [, int &$line ]] )

Checks if or where headers have been sent.

You can't add any more header lines using the header() function once the header block has already been sent. Using this function you can at least prevent getting HTTP header related error messages. Another option is to use Output Buffering.

인수

file: If the optional file and line parameters are set, headers_sent() will put the PHP source file name and line number where output started in the file and line variables.
line: The line number where the output started.

반환값

headers_sent() will return FALSE if no HTTP headers have already been sent or TRUE otherwise.

예제

Example #1 Examples using headers_sent()


<?php

// If no headers are sent, send one
if (!headers_sent()) {
    header('Location: http://www.example.com/');
    exit;
}

// An example using the optional file and line parameters, as of PHP 4.3.0
// Note that $filename and $linenum are passed in for later use.
// Do not assign them values beforehand.
if (!headers_sent($filename, $linenum)) {
    header('Location: http://www.example.com/');
    exit;

// You would most likely trigger an error here.
} else {

    echo "Headers already sent in $filename on line $linenum\n" .
          "Cannot redirect, for now please click this <a " .
          "href=\"http://www.example.com\">link</a> instead\n";
    exit;
}

?>

주의

Note:
헤더는 SAPI에서 사용할 수 있을 경우에만 접근하고 출력할 수 있습니다.

참고

ob_start() - 출력 버퍼링을 켭니다
trigger_error() - Generates a user-level error/warning/notice message
headers_list() - Returns a list of response headers sent (or ready to send)
header() - Send a raw HTTP header for a more detailed discussion of the matters involved.