Warning cannot send session Cookie-headers already sent. Resolution of the problem (PHP UTF-8 BOM citation

Warning cannot send session cookie-headers already sent ... Problem Resolution (PHP UTF-8 BOM citation
Accustomed to using Edit plus PHP programming, so sometimes there are some unknown errors, very troublesome;
Recently, when developing a project, some pages always have the following issues:

Warning:session_start () [Function.session-start]: Cannot send session cookie-headers already sent by (output started at e:\web\apache2\htdocs\index.php:1) in E:\web\Apache2\htdocs\functions\sessions.php on line 67

Warning:session_start () [Function.session-start]: Cannot send session cache Limiter-headers already sent (output Starte D at E:\web\apache2\htdocs\index.php:1) in E:\web\Apache2\htdocs\functions\sessions.php on line 67
After a detailed search, get the following reasons:
The default encoding for Utf-8 is set in my edit Plus, and the utf_8 signature is: Always add a signature;
So try these things:
In the file->utf_8 signature of the Edit Plus tool, change the option "Always add signature" to "always remove signature", then open the index.php file and re-save as, rerun the script and finally OK;

In addition, found on the Internet two more reference value of the article, I hope someone encounters this kind of situation can be solved perfectly!


One UTF-8 BOM caused by PHP's bizarre problem

---a.php
Header ("Content-type:image/bmp");
Session_Start ();
................
?>
Save a.php in utf-8 format, the result of the browser access to this PHP file, there will be the following error:
Warning:session_start () [Function.session-start]: Cannot send session cache Limiter-headers already sent (output Starte D

atxxx.php:1) Inxxxon Line 2

This problem is very common, mostly because there is output before session_start! For the veteran, this error will not happen, but if you are using DW or EditPlus

If the editor writes code, even a master can have this error!

As the above tip: in the 1th line of the xxx file, xxx file 2nd line, as you see, these two will not have any output statements, very strange or error, why?
Originally:

A Unicode signature (BOM) can include a byte order mark (BOM) in a document. A BOM is 2 to 4 bytes at the beginning of a text file, which identifies the file as Unicode, and if this

And also identifies the byte order of the subsequent bytes. Because UTF-8 does not have byte order, you can choose to add a UTF-8 BOM. For UTF-16 and UTF-32, this is required.
See, No! If this option is selected, it will output 2 to 4 bytes at the front of the page!

and Session_Start () requires no output to the client browser


Second, there is another place where errors can occur, such as:
/--a.php--
?>
Blank Line
Blank Line

If you include a.php after you come back there will also be this problem, usually the advice is often included in the end of the file does not have?>

Another example:
You cannot have any output before calling Session_Start (). For example, the following is wrong
The wrong.
==========================================
1 rows
2 rows 3 lines session_start ();//before the first line already has output
4 lines .....
5 Row?>
==========================================

has been tested, the facts are really so bizarre.

Three

Session_Start ()
Set_cookie ()
Header ()
[Email protected]


Four
In the EditPlus editor, if you first convert the Utf-8 a.php file to gb2312 or other, and then convert to Utf-8, you can access it successfully, that is, the file at the beginning of the

BOM is removed, this time the UTF-8 is no BOM type


php-session_start () error caused by Utf-8 encoding problem


Big Small
With the default gb2312 encoding, ANSI encoding is compatible, the header of the file has no additional information, and session_start () can work correctly at this time.
With UTF encoding, most editors attach a BOM block to the head of the file, and my editplus is attached with FF FE, with the 16-input editor
Can be seen very clearly. This way, when Session_Start () is called, it actually outputs two bytes to the browser, except for the invisible word Fu Yi
The following warning appears in the Navigator:
Warning:session_start () [Function.session-start]: Cannot send session cookie-headers already sent by (output started at ......................

Workaround:
1, manual removal of BOM block, can be edited in the 16 editor, such as UltraEdit, or with the editor's own features, a good editor generally provides a choice whether to remove BOM block.
2. Write your own script corrections, which are defined for different editors, BOM headers:
UTF-8 EF BB BF
UTF-16 Big Endian FE FF
UTF-16 Little Endian FF FE
UTF-32 Big Endian (FE FF)
UTF-32 Little Endian FF FE 00 00

