PHP in front of the header output is not reported warning hint

Before the header or session_start () and so on can not have output bar, otherwise will be reported warning level error, but why not reported.
Version: 5.3.5
With the Wamp

    
 
Jumped away, changed to Session_Start () did not report
Error level php.ini setting is error_reporting = E_all | E_strict
                                                    
                                                                                                                                             
Reply content:
                                                                                  
Before the header or session_start () and so on can not have output bar, otherwise will be reported warning level error, but why not reported.
Version: 5.3.5
With the Wamp
    
  
Jumped away, changed to Session_Start () did not report
Error level php.ini setting is error_reporting = E_all | E_strict
                                                                
                                    
Look at Phpinfo (), is not the output_buffering open. If it is, it will be fine.
                                        
                                    
Confirm whether there is warning hint:

  
  

   
   
 
    
See if there's no print on the page, you've seen it, no
 
    
Look at the error log there is no, xampp/wamp default settings are more security-oriented (rather than the default focus on the development of Ease of use), will not show the error message directly on the page
 
   
  
  
If you've seen it, you still can't find the warning record, check why it's not showing or log in (assuming it generates warning):
Print phpinfo () confirm which php.ini file your environment is loading, and locate the php.ini file.

  
  

   
   
 
    
Check the error_reporting settings (you have checked, but are not sure if you are using another INI file)
 
    
Check display_error settings
 
    
Check error_log settings
 
   
  
  
If the above checks are OK (INI file is configured to require warning, you are not found in the log file), the current environment configuration does not produce warning, then press the upstairs felix021 said to see the output buffer settings
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