Questions about PHP output XML files

Concerning the PHP output XML file, PHPeach's xml Content will automatically hide the xml tag in the browser, so I added the header (& quot; Content-type: text/xml & quot;); but the problem occurs. it is normal to output the content before it is not added (view the webpage source file), but the problem about PHP output XML file
PHP each xml content is automatically hidden in the browser.

So I added header ("Content-type: text/xml ");

However, if the problem occurs, it is normal to output the content before it is added (view the webpage source file). However, once the header is added, only a part of the content is output and the output is stuck.

As follows:
Normal situation:
? I'm a pig, I'm a pig

After adding the header:
I'm a pig.

The content gets stuck.

------ Solution --------------------
Will the php environment on your laptop be inconsistent with that on the server! Check it!