web中的字符问题总结

计算机中的字符表示都是2进制，1B（字节）=8bit 用八个内存单元为一个位标号（编码），这是ASCII编码 8bit用了7bit 2^7=128个 扩展的ASCII用了8bit 2^8=256个

256对汉字是远远不够，代替汉字就要用多位表示，gb2312是2字节 utf8是3字节

1、ASCII表中的字符分 为可打印与非打印字符

非打印字符 ： 0-31 + 127

剩下的是可打印字符

ASCII码表

Bin	Dec	Hex	缩写/字符	解释
00000000	0	00	NUL(null)	空字符
00000001	1	01	SOH(start of headling)	标题开始
00000010	2	02	STX (start of text)	正文开始
00000011	3	03	ETX (end of text)	正文结束
00000100	4	04	EOT (end of transmission)	传输结束
00000101	5	05	ENQ (enquiry)	请求
00000110	6	06	ACK (acknowledge)	收到通知
00000111	7	07	BEL (bell)	响铃
00001000	8	08	BS (backspace)	退格
00001001	9	09	HT (horizontal tab)	水平制表符
00001010	10	0A	LF (NL line feed, new line)	换行键
00001011	11	0B	VT (vertical tab)	垂直制表符
00001100	12	0C	FF (NP form feed, new page)	换页键
00001101	13	0D	CR (carriage return)	回车键
00001110	14	0E	SO (shift out)	不用切换
00001111	15	0F	SI (shift in)	启用切换
00010000	16	10	DLE (data link escape)	数据链路转义
00010001	17	11	DC1 (device control 1)	设备控制1
00010010	18	12	DC2 (device control 2)	设备控制2
00010011	19	13	DC3 (device control 3)	设备控制3
00010100	20	14	DC4 (device control 4)	设备控制4
00010101	21	15	NAK (negative acknowledge)	拒绝接收
00010110	22	16	SYN (synchronous idle)	同步空闲
00010111	23	17	ETB (end of trans. block)	传输块结束
00011000	24	18	CAN (cancel)	取消
00011001	25	19	EM (end of medium)	介质中断
00011010	26	1A	SUB (substitute)	替补
00011011	27	1B	ESC (escape)	溢出
00011100	28	1C	FS (file separator)	文件分割符
00011101	29	1D	GS (group separator)	分组符
00011110	30	1E	RS (record separator)	记录分离符
00011111	31	1F	US (unit separator)	单元分隔符
00100000	32	20	(space)	空格
00100001	33	21	!
00100010	34	22	"
00100011	35	23	#
00100100	36	24	$
00100101	37	25	%
00100110	38	26	&
00100111	39	27	'
00101000	40	28	(
00101001	41	29	)
00101010	42	2A	*
00101011	43	2B	+
00101100	44	2C	,
00101101	45	2D	-
00101110	46	2E	.
00101111	47	2F	/
00110000	48	30	0
00110001	49	31	1
00110010	50	32	2
00110011	51	33	3
00110100	52	34	4
00110101	53	35	5
00110110	54	36	6
00110111	55	37	7
00111000	56	38	8
00111001	57	39	9
00111010	58	3A	:
00111011	59	3B	;
00111100	60	3C	<
00111101	61	3D	=
00111110	62	3E	>
00111111	63	3F	?
01000000	64	40	@
01000001	65	41	A
01000010	66	42	B
01000011	67	43	C
01000100	68	44	D
01000101	69	45	E
01000110	70	46	F
01000111	71	47	G
01001000	72	48	H
01001001	73	49	I
01001010	74	4A	J
01001011	75	4B	K
01001100	76	4C	L
01001101	77	4D	M
01001110	78	4E	N
01001111	79	4F	O
01010000	80	50	P
01010001	81	51	Q
01010010	82	52	R
01010011	83	53	S
01010100	84	54	T
01010101	85	55	U
01010110	86	56	V
01010111	87	57	W
01011000	88	58	X
01011001	89	59	Y
01011010	90	5A	Z
01011011	91	5B	[
01011100	92	5C	\
01011101	93	5D	]
01011110	94	5E	^
01011111	95	5F	_
01100000	96	60	`
01100001	97	61	a
01100010	98	62	b
01100011	99	63	c
01100100	100	64	d
01100101	101	65	e
01100110	102	66	f
01100111	103	67	g
01101000	104	68	h
01101001	105	69	i
01101010	106	6A	j
01101011	107	6B	k
01101100	108	6C	l
01101101	109	6D	m
01101110	110	6E	n
01101111	111	6F	o
01110000	112	70	p
01110001	113	71	q
01110010	114	72	r
01110011	115	73	s
01110100	116	74	t
01110101	117	75	u
01110110	118	76	v
01110111	119	77	w
01111000	120	78	x
01111001	121	79	y
01111010	122	7A	z
01111011	123	7B	{
01111100	124	7C	|
01111101	125	7D	}
01111110	126	7E	~
01111111	127	7F	DEL (delete)	删除

9    制表符  \t

10  换行符  \r

13  回车符  \n

2 浏览器对url的编码

浏览器会对表单中的key/val 进行编码之后再传递 php脚本会自动将之解码

编码规则： %+字符对应的十六进制

这个是HTML实体的对照表：

php函数中 html_entity_decode 函数将HTML实体转化成对应的char，

HTML实体表示方式 &entity_name; &#numner;（数字可以是10进制与十六进制x两种）

php函数 html_entity_decode 的一个bug就是 不能识别 没有分号的，但是这种没有分号的却可以被浏览器识别

字符	十进制字符编号	实体名字	说明
---	�	---	未使用Unused
---		---	未使用Unused
---		---	未使用Unused
---		---	未使用Unused
---		---	未使用Unused
---		---	未使用Unused
---		---	未使用Unused
---		---	未使用Unused
---		---	未使用Unused
---		---	制表符Horizontal tab
---		---	换行Line feed
---		---	未使用Unused
---		---	未使用Unused
---		---	回车Carriage Return
---		---	未使用Unused
---		---	未使用Unused
---		---	未使用Unused
---		---	未使用Unused
---		---	未使用Unused
---		---	未使用Unused
---		---	未使用Unused
---		---	未使用Unused
---		---	未使用Unused
---		---	未使用Unused
---		---	未使用Unused
---		---	未使用Unused
---		---	未使用Unused
---		---	未使用Unused
---		---	未使用Unused
---		---	未使用Unused
---		---	未使用Unused
---		---	未使用Unused
		---	Space
!	!	---	惊叹号Exclamation mark
"	"	"	双引号Quotation mark
#	#	---	数字标志Number sign
$	$	---	美元标志Dollar sign
%	%	---	百分号Percent sign
&	&	&	Ampersand
"	'	---	单引号Apostrophe
(	(	---	小括号左边部分Left parenthesis
)	)	---	小括号右边部分Right parenthesis
*	*	---	星号Asterisk
+	+	---	加号Plus sign
,	,	---	逗号Comma
-	-	---	连字号Hyphen
.	.	---	句号Period (fullstop)
/	/	---	斜杠Solidus (slash)
0	0	---	数字0 Digit 0
1	1	---	数字1 Digit 1
2	2	---	数字2 Digit 2
3	3	---	数字3 Digit 3
4	4	---	数字4 Digit 4
5	5	---	数字5 Digit 5
6	6	---	数字6 Digit 6
7	7	---	数字7 Digit 7
8	8	---	数字8 Digit 8
9	9	---	数字9 Digit 9
:	:	---	冒号Colon
;	;	---	分号Semicolon
<	<	<	小于号Less than
=	=	---	等于符号Equals sign
>	>	>	大于号Greater than
?	?	---	问号Question mark
@	@	---	Commercial at
A	A	---	大写A Capital A
B	B	---	大写B Capital B
C	C	---	大写C Capital C
D	D	---	大写D Capital D
E	E	---	大写E Capital E
F	F	---	大写F Capital F
G	G	---	大写G Capital G
H	H	---	大写H Capital H
I	I	---	大写J Capital I
J	J	---	大写K Capital J
K	K	---	大写L Capital K
L	L	---	大写K Capital L
M	M	---	大写M Capital M
N	N	---	大写N Capital N
O	O	---	大写O Capital O
P	P	---	大写P Capital P
Q	Q	---	大写Q Capital Q
R	R	---	大写R Capital R
S	S	---	大写S Capital S
T	T	---	大写T Capital T
U	U	---	大写U Capital U
V	V	---	大写V Capital V
W	W	---	大写W Capital W
X	X	---	大写X Capital X
Y	Y	---	大写Y Capital Y
Z	Z	---	大写Z Capital Z
[	[	---	中括号左边部分Left square bracket
/	\	---	反斜杠Reverse solidus (backslash)
]	]	---	中括号右边部分Right square bracket
^	^	---	Caret
_	_	---	下划线Horizontal bar (underscore)
`	`	---	尖重音符Acute accent
a	a	---	小写a Small a
b	b	---	小写b Small b
c	c	---	小写c Small c
d	d	---	小写d Small d
e	e	---	小写e Small e
f	f	---	小写f Small f
g	g	---	小写g Small g
h	h	---	小写h Small h
i	i	---	小写i Small i
j	j	---	小写j Small j
k	k	---	小写k Small k
l	l	---	小写l Small l
m	m	---	小写m Small m
n	n	---	小写n Small n
o	o	---	小写o Small o
p	p	---	小写p Small p
q	q	---	小写q Small q
r	r	---	小写r Small r
s	s	---	小写s Small s
t	t	---	小写t Small t
u	u	---	小写u Small u
v	v	---	小写v Small v
w	w	---	小写w Small w
x	x	---	小写x Small x
y	y	---	小写y Small y
z	z	---	小写z Small z
｛	{	---	大括号左边部分Left curly brace
|	|	---	竖线Vertical bar
｝	}	---	大括号右边部分Right curly brace
~	~	---	Tilde
---		---	未使用Unused
			空格Nonbreaking space
?	¡	¡	Inverted exclamation
￠	¢	¢	货币分标志Cent sign
￡	£	£	英镑标志Pound sterling
¤	¤	¤	通用货币标志General currency sign
￥	¥	¥	日元标志Yen sign
|	¦	¦ or &brkbar;	断竖线Broken vertical bar
§	§	§	分节号Section sign
¨	¨	¨ or ¨	变音符号Umlaut
?	©	©	版权标志Copyright
a	ª	ª	Feminine ordinal
?	«	«	Left angle quote, guillemet left
?	¬	¬	Not sign
	­	­	Soft hyphen
?	®	®	注册商标标志Registered trademark
ˉ	¯	¯ or &hibar;	长音符号Macron accent
°	°	°	度数标志Degree sign
±	±	±	加或减Plus or minus
2	²	²	上标2 Superscript two
3	³	³	上标3 Superscript three
′	´	´	尖重音符Acute accent
μ	µ	µ	Micro sign
?	¶	¶	Paragraph sign
·	·	·	Middle dot
?	¸	¸	Cedilla
1	¹	¹	上标1 Superscript one
o	º	º	Masculine ordinal
?	»	»	Right angle quote, guillemet right
?	¼	¼	四分之一Fraction one-fourth
?	½	½	二分之一Fraction one-half
?	¾	¾	四分之三Fraction three-fourths
?	¿	¿	Inverted question mark
à	À	À	Capital A, grave accent
á	Á	Á	Capital A, acute accent
?	Â	Â	Capital A, circumflex
?	Ã	Ã	Capital A, tilde
?	Ä	Ä	Capital A, di?esis / umlaut
?	Å	Å	Capital A, ring
?	Æ	Æ	Capital AE ligature
?	Ç	Ç	Capital C, cedilla
è	È	È	Capital E, grave accent
é	É	É	Capital E, acute accent
ê	Ê	Ê	Capital E, circumflex
?	Ë	Ë	Capital E, di?esis / umlaut
ì	Ì	Ì	Capital I, grave accent
í	Í	Í	Capital I, acute accent
?	Î	Î	Capital I, circumflex
?	Ï	Ï	Capital I, di?esis / umlaut
D	Ð	Ð	Capital Eth, Icelandic
?	Ñ	Ñ	Capital N, tilde
ò	Ò	Ò	Capital O, grave accent
ó	Ó	Ó	Capital O, acute accent
?	Ô	Ô	Capital O, circumflex
?	Õ	Õ	Capital O, tilde
?	Ö	Ö	Capital O, di?esis / umlaut
×	×	×	乘号Multiply sign
?	Ø	Ø	Capital O, slash
ù	Ù	Ù	Capital U, grave accent
ú	Ú	Ú	Capital U, acute accent
?	Û	Û	Capital U, circumflex
ü	Ü	Ü	Capital U, di?esis / umlaut
Y	Ý	Ý	Capital Y, acute accent
T	Þ	Þ	Capital Thorn, Icelandic
?	ß	ß	Small sharp s, German sz
à	à	à	Small a, grave accent
á	á	á	Small a, acute accent
a	â	â	Small a, circumflex
?	ã	ã	Small a, tilde
?	ä	ä	Small a, di?esis / umlaut
?	å	å	Small a, ring
?	æ	æ	Small ae ligature
?	ç	ç	Small c, cedilla
è	è	è	Small e, grave accent
é	é	é	Small e, acute accent
ê	ê	ê	Small e, circumflex
?	ë	ë	Small e, di?esis / umlaut
ì	ì	ì	Small i, grave accent
í	í	í	Small i, acute accent
?	î	î	Small i, circumflex
?	ï	ï	Small i, di?esis / umlaut
e	ð	ð	Small eth, Icelandic
?	ñ	ñ	Small n, tilde
ò	ò	ò	Small o, grave accent
ó	ó	ó	Small o, acute accent
?	ô	ô	Small o, circumflex
?	õ	õ	Small o, tilde
?	ö	ö	Small o, di?esis / umlaut
÷	÷	÷	除号Division sign
?	ø	ø	Small o, slash
ù	ù	ù	Small u, grave accent
ú	ú	ú	Small u, acute accent
?	û	û	Small u, circumflex
ü	ü	ü	Small u, di?esis / umlaut
y	ý	ý	Small y, acute accent
t	þ	þ	Small thorn, Icelandic
?	ÿ	ÿ	Small y, umlaut