BOM Header Issues

Recently there are many on the micro-blog to discuss the BOM head problem, BOM header will cause the page display garbled, XML analysis problems. And I happen to encounter a situation in the WML page if the BOM header, PC Browser (IE, Firefox) and Mobile browser (UC) are normal, and if the BOM header, the phone is normal, the PC side is not normal. For this reason, the BOM head and coding do some simple research.

　　

1, what is the BOM header

For Notepad that uses Windows to edit text, when saved with UTF-8 encoding, the text is added three invisible bytes 0xEF 0xBB 0xBF, some articles refer to these three bytes as three characters is wrong, in fact, if the three bytes decoded according to UTF-8, Represents a character, this character is not displayed, and is different from the space, let's first convert the three bytes into a

Coding	UTF8 Encoding 16 binary	Unicode encoding 16 binary	Unicode encoding 10 binary
Value	Efbbbf	FEFF	65279

　　

Check out the tool for viewing Chinese characters on the Web by Encoding (http://www.mytju.com/classcode/tools/encode_utf8.asp)

　　

　　

As you can see, this is a character without any display, so what is the use of such a character? In fact, this character is used by the Windows text Editor as a token of character encoding, under Windows System, once the first three bytes of text is found to be EFBBBF, then the entire text is confirmed to be encoded according to Utf-8.

2, the general process of BOM head

　　A, Linux to see if the file has a BOM header method

A typical Linux server has a XXD command that can be opened as a 16-binary view.

　　b, see which files under the project have BOM header

Many methods, online generally provide grep-r-i-l $ ' ^\xef\xbb\xbf './That is, under a project, the loop project inside the file, not case-sensitive, to see whether it has a hex under the EFBBBF beginning of the file, output file name information

　　C, remove BOM head

Single file removal BOM head can be opened with VI file, set Nobomb after saving can be removed, the same way if you want to add BOM head, set bomb can, and if you remove all of the items that exist in the BOM header files, generally need to write scripts to implement, under PHP
A1, looping through each file
B1, using substr () to view the first three bytes of a file, turn bytes into decimal view
"EF" = 239
"BB" = 187
"BF" = 191
C1, if you see the first three bytes is the BOM header, then substr () after the interception of text written

BOM Header Issues