phpexcel的奇怪行为

Question

When trying to get an Excel spreadsheet from php with phpexcel, strange characters are generated in the output if a constant definition (DEFINE (' var',' value') is added. My code

header('Content-Type: application/vnd.ms-excel');
header('Content-Disposition: attachment;filename="theFile.xls"');
header('Cache-Control: max-age=0');

require_once '../config.php';
include 'PHPExcel.php';
$excel = new PHPExcel();

$writer = PHPExcel_IOFactory::createWriter($excel, 'Excel5');

$excel->setActiveSheetIndex(0);
$excel->getActiveSheet()->SetCellValue('A1', 'Hello');
$excel->getActiveSheet()->SetCellValue('B2', 'world!');
$writer->save('php://output');      

I don't understand the reason, since config. php is all it contains.

If I delete the config. php line, the excel file is generated correctly Does anyone know what this behavior is due to?

this code runs smoothly

header('Content-Type: application/vnd.ms-excel');
header('Content-Disposition: attachment;filename="theFile.xls"');
header('Cache-Control: max-age=0');

include 'PHPExcel.php';
$excel = new PHPExcel();

$writer = PHPExcel_IOFactory::createWriter($excel, 'Excel5');

$excel->setActiveSheetIndex(0);
$excel->getActiveSheet()->SetCellValue('A1', 'Hello');
$excel->getActiveSheet()->SetCellValue('B2', 'world!');
$writer->save('php://output');      

config.php content

define('DB_HOST', 'myHost');
define('DB_USER', 'myUser');
define('DB_PASSWORD', 'myPass');
define('DB_DATABASE', 'myDB');

Answer 1

I finally found it. the output to the excel file does not allow ECHO or any other type of text output, in my case the config file had a blank line at the beginning

--->here
<?php 
define('DB_HOST', 'myHost');
define('DB_USER', 'myUser');

etc.