The session may indicate that the header has been output

The session or header indicates that a header message has been exported.
Let me summarize the question.
1: At the beginning of the jump, the prompt error, and then I replaced the HTML jump, because I use the WAMP integration environment, I am afraid it is environmental problems, there is no big debugging.
2:session (), or prompt, I am sure that there is no output before, but this is still the hint. I've found so many ways to test it.

File included (include * *)
1) Save as UTF8 for BOM mode, Still,
2) Var_dump (Headers_sent ()); If the kill contains the display 0, do not delete the containing file will show 1.

Ability to limit, Baidu has done, but also look big hand to help me.

------Solution--------------------
Output started at d:\wamp\www\blog\class\db.class.php:1
Output in D:\wamp\www\Blog\class\DB.class.php line 1th

Why not turn a blind eye to such a simple and clear hint?

