ASCII 码

控制字符（33）

Control Characters
DEC	OCT	HEX	BIN	Symbol	Caret Notation	Description
0	000	00	00000000	NUL	^@	Null character, \0
1	001	01	00000001	SOH	^A	Start of Heading
2	002	02	00000010	STX	^B	Start of Text
3	003	03	00000011	ETX	^C	End of Text
4	004	04	00000100	EOT	^D	End of Transmission
5	005	05	00000101	ENQ	^E	Enquiry
6	006	06	00000110	ACK	^F	Acknowledge
7	007	07	00000111	BEL	^G	Bell, Alert, \a
8	010	08	00001000	BS	^H	Backspace, \b
9	011	09	00001001	HT	^I	Horizontal Tabulation, \t
10	012	0A	00001010	LF	^J	Line Feed, \n
11	013	0B	00001011	VT	^K	Vertical Tabulation, \v
12	014	0C	00001100	FF	^L	Form Feed, \f
13	015	0D	00001101	CR	^M	Carriage Return, \r
14	016	0E	00001110	SO	^N	Shift Out
15	017	0F	00001111	SI	^O	Shift In
16	020	10	00010000	DLE	^P	Data Link Escape
17	021	11	00010001	DC1	^Q	Device Control One (XON)
18	022	12	00010010	DC2	^R	Device Control Two
19	023	13	00010011	DC3	^S	Device Control Three (XOFF)
20	024	14	00010100	DC4	^T	Device Control Four
21	025	15	00010101	NAK	^U	Negative Acknowledge
22	026	16	00010110	SYN	^V	Synchronous Idle
23	027	17	00010111	ETB	^W	End of Transmission Block
24	030	18	00011000	CAN	^X	Cancel
25	031	19	00011001	EM	^Y	End of Medium
26	032	1A	00011010	SUB	^Z	Substitute
27	033	1B	00011011	ESC	^[	Escape, \e
28	034	1C	00011100	FS	^\	File Separator
29	035	1D	00011101	GS	^]	Group Separator
30	036	1E	00011110	RS	^^	Record Separator
31	037	1F	00011111	US	^_	Unit Separator
127	177	7F	01111111	DEL	^?	Delete

Shell 中使用 cat -vET file 可以打印出一些 Caret Notation 格式的字符。

制表符

制表符（Tab）不是可打印字符，因为它不是用于显示某个具体字符，更不代表固定长度的空白字符，而是用于控制文本的格式和布局。

假设在 HTML 的 <pre> 元素中插入这样一段源码：

&#9;This line begins with a single tab.
Here&#9;are&#9;some&#9;more&#9;tab&#9;characters&#9;!
T.......T.......T.......T.......T.......T.......T.......T

网页中显示的效果如下（默认 tab-size 为 8）：

	This line begins with a single tab.
Here	are	some	more	tab	characters	!
T.......T.......T.......T.......T.......T.......T.......T

满足：

\[(\mathrm{wordLength} + \mathrm{tabSpaceLength})\ \% \ \mathrm{tabSize} = 0\]

使用文本编辑器时，可以设置按 Tab 键插入一个制表符，或者插入固定长度的空格（一般默认为 4 个空格）。

可打印字符（95）

Printable Characters
DEC	OCT	HEX	BIN	Symbol	HTML Number	HTML Name	Description
32	040	20	00100000	SP			Space
33	041	21	00100001	!	!	&excl;	Exclamation mark
34	042	22	00100010	“	"	"	Double quotes, Speech marks
35	043	23	00100011	#	#	&num;	Number sign
36	044	24	00100100	$	$	&dollar;	Dollar
37	045	25	00100101	%	%	&percnt;	Percent sign
38	046	26	00100110	&	&	&	Ampersand
39	047	27	00100111	‘	'	'	Single quote
40	050	28	00101000	(	(	&lparen;	Open parenthesis, Open bracket
41	051	29	00101001	)	)	&rparen;	Close parenthesis, Close bracket
42	052	2A	00101010	*	*	&ast;	Asterisk
43	053	2B	00101011	+	+	+	Plus
44	054	2C	00101100	,	,	,	Comma
45	055	2D	00101101	-	-		Hyphen, Minus
46	056	2E	00101110	.	.	&period;	Period, Dot, Full stop
47	057	2F	00101111	/	/	/	Slash, Divide
48	060	30	00110000	0	0		Zero
49	061	31	00110001	1	1		One
50	062	32	00110010	2	2		Two
51	063	33	00110011	3	3		Three
52	064	34	00110100	4	4		Four
53	065	35	00110101	5	5		Five
54	066	36	00110110	6	6		Six
55	067	37	00110111	7	7		Seven
56	070	38	00111000	8	8		Eight
57	071	39	00111001	9	9		Nine
58	072	3A	00111010	:	:	&colon;	Colon
59	073	3B	00111011	;	;	&semi;	Semicolon
60	074	3C	00111100	<	<	<	Less than, Open angled bracket
61	075	3D	00111101	=	=	=	Equals
62	076	3E	00111110	>	>	>	Greater than, Close angled bracket
63	077	3F	00111111	?	?	&quest;	Question mark
64	100	40	01000000	@	@	&commat;	At sign
65	101	41	01000001	A	A		Uppercase A
66	102	42	01000010	B	B		Uppercase B
67	103	43	01000011	C	C		Uppercase C
68	104	44	01000100	D	D		Uppercase D
69	105	45	01000101	E	E		Uppercase E
70	106	46	01000110	F	F		Uppercase F
71	107	47	01000111	G	G		Uppercase G
72	110	48	01001000	H	H		Uppercase H
73	111	49	01001001	I	I		Uppercase I
74	112	4A	01001010	J	J		Uppercase J
75	113	4B	01001011	K	K		Uppercase K
76	114	4C	01001100	L	L		Uppercase L
77	115	4D	01001101	M	M		Uppercase M
78	116	4E	01001110	N	N		Uppercase N
79	117	4F	01001111	O	O		Uppercase O
80	120	50	01010000	P	P		Uppercase P
81	121	51	01010001	Q	Q		Uppercase Q
82	122	52	01010010	R	R		Uppercase R
83	123	53	01010011	S	S		Uppercase S
84	124	54	01010100	T	T		Uppercase T
85	125	55	01010101	U	U		Uppercase U
86	126	56	01010110	V	V		Uppercase V
87	127	57	01010111	W	W		Uppercase W
88	130	58	01011000	X	X		Uppercase X
89	131	59	01011001	Y	Y		Uppercase Y
90	132	5A	01011010	Z	Z		Uppercase Z
91	133	5B	01011011	[	[	[	Opening bracket
92	134	5C	01011100	\	\	\	Backslash
93	135	5D	01011101	]	]	]	Closing bracket
94	136	5E	01011110	^	^	&Hat;	Caret, Circumflex
95	137	5F	01011111	_	_	&lowbar;	Underscore
96	140	60	01100000	`	`	&grave;	Grave accent
97	141	61	01100001	a	a		Lowercase a
98	142	62	01100010	b	b		Lowercase b
99	143	63	01100011	c	c		Lowercase c
100	144	64	01100100	d	d		Lowercase d
101	145	65	01100101	e	e		Lowercase e
102	146	66	01100110	f	f		Lowercase f
103	147	67	01100111	g	g		Lowercase g
104	150	68	01101000	h	h		Lowercase h
105	151	69	01101001	i	i		Lowercase i
106	152	6A	01101010	j	j		Lowercase j
107	153	6B	01101011	k	k		Lowercase k
108	154	6C	01101100	l	l		Lowercase l
109	155	6D	01101101	m	m		Lowercase m
110	156	6E	01101110	n	n		Lowercase n
111	157	6F	01101111	o	o		Lowercase o
112	160	70	01110000	p	p		Lowercase p
113	161	71	01110001	q	q		Lowercase q
114	162	72	01110010	r	r		Lowercase r
115	163	73	01110011	s	s		Lowercase s
116	164	74	01110100	t	t		Lowercase t
117	165	75	01110101	u	u		Lowercase u
118	166	76	01110110	v	v		Lowercase v
119	167	77	01110111	w	w		Lowercase w
120	170	78	01111000	x	x		Lowercase x
121	171	79	01111001	y	y		Lowercase y
122	172	7A	01111010	z	z		Lowercase z
123	173	7B	01111011	{	{	{	Opening brace
124	174	7C	01111100	\|	\|	\|	Vertical bar
125	175	7D	01111101	}	}	}	Closing brace
126	176	7E	01111110	~	~	&tilde;	Equivalency sign, Tilde

参考资料

ASCII Table

https://www.ascii-code.com/

ASCII

https://en.wikipedia.org/wiki/ASCII