什么是BOM（Byte Order Mark）？

更新时间：2022-09-02 12:33:13

BOM（Byte Order Mark），字节顺序标记，出现在文本文件头部，Unicode编码标准中用于标识文件是采用哪种格式的编码，但它对于文件的读者来说是不可见字符。

下表列出不同的字符编码的BOM

编码	BOM (十六进制)	BOM (十进制)	CP1252 字符
UTF-8^{[t 1]}	`EF BB BF`	`239 187 191`	`ï»¿`
UTF-16 (BE)	`FE FF`	`254 255`	`þÿ`
UTF-16 (LE)	`FF FE`	`255 254`	`ÿþ`
UTF-32 (BE)	`00 00 FE FF`	`0 0 254 255`	`␀␀þÿ` (␀ refers to the ASCII null character)
UTF-32 (LE)	`FF FE 00 00`	`255 254 0 0`	`ÿþ␀␀` (␀ refers to the ASCII null character)
UTF-7^{[t 1]}	`2B 2F 76 38` `2B 2F 76 39` `2B 2F 76 2B` `2B 2F 76 2F`^{[t 2]} `2B 2F 76 38 2D`^{[t 3]}	`43 47 118 56` `43 47 118 57` `43 47 118 43` `43 47 118 47` `43 47 118 56 45`	`+/v8` `+/v9` `+/v+` `+/v/` `+/v8-`
UTF-1^{[t 1]}	`F7 64 4C`	`247 100 76`	`÷dL`
UTF-EBCDIC^{[t 1]}	`DD 73 66 73`	`221 115 102 115`	`Ýsfs`
SCSU^{[t 1]}	`0E FE FF`^{[t 4]}	`14 254 255`	`␎þÿ` (␎ represents the ASCII “shift out” character)
BOCU-1^{[t 1]}	`FB EE 28`	`251 238 40`	`ûî(`
GB-18030^{[t 1]}	`84 31 95 33`	`132 49 149 51`	`„1•3`