Question

可能重复：
  “Warning: Cannot modify header information - headers already sent by” error
  Headers already sent by PHP

我发出警告说：

Warning: Cannot modify header information - headers already sent by (output started at C:\xampp\htdocs\projects\wesm\intranet\plugins\company_calendar\calendarpdf.php:90) in C:\xampp\htdocs\projects\wesm\intranet\plugins\company_calendar\mpdf\mpdf.php on line 7236

Warning: Cannot modify header information - headers already sent by (output started at C:\xampp\htdocs\projects\wesm\intranet\plugins\company_calendar\calendarpdf.php:90) in C:\xampp\htdocs\projects\wesm\intranet\plugins\company_calendar\mpdf\mpdf.php on line 1827
mPDF error: Some data has already been output to browser, can't send PDF file

你可以给我一些建议来摆脱那些警告..

以下是我的一些代码：

<?php

include "admin/include/connect.php";
include "include/calendarFunction.php";
$function   = new calendarFunction();
$cMonth     = $_GET['cMonth'];
$cYear      = $_GET['cYear'];

$htmldata = $function->calendarPDF($cMonth, $cYear);

$currString = $htmldata;
$stringtoDelete  = '';
$newCurrString = str_replace($stringtoDelete, " ", $currString);
$html = $newCurrString ;
include("mpdf/mpdf.php");

$mpdf=new mPDF(); 
$mpdf->AddPage('L');

$mpdf->WriteHTML($html);
$mpdf->Output('calendar.pdf','I');
exit;

?>

Answer 1

如果在标题之前使用echo，则会出现此错误。

例如：

<?php
   echo "Some String";
   header("location:redirect.php");
?>

你需要在文件中的任何其他内容之前发送标题，包括php

之外的html

<?php
   header("location:redirect.php");
   echo "Some String";
?>

Answer 2

请先检查标题功能之前是否有空格，或者在页面调用标题功能之前检查"echo"。

警告：无法修改标头信息 - 已发送的标头

2 个答案: