ASCII encoding table-HTML Tutorial-php.cn

ASCII is the abbreviation of American Standard Code for Information Interchange. ASCII code is currently the most common coding standard for computers. Because computers can only accept numeric information, ASCII codes represent characters as numbers so that the computer can accept and process them. For example, the ASCII code for the capital letter A is 65. In the ASCII code, Nos. 0 to 32 and No. 127 are control characters, commonly used ones are LF (line feed) and CR (carriage return); Nos. 33 to 126 are characters, of which Nos. 48 to 57 are 0 to 9 Arabic numerals; numbers 65 to 90 are 26 uppercase English letters, numbers 97 to 122 are 26 lowercase English letters, and the rest are some punctuation marks, arithmetic symbols, etc.

　ASCII character encoding table

ASCII value	Control characters	ASCII value	Control characters	ASCII value	Control characters	ASCII value	Control characters
0	NUT	32	(space)	64	@	96	,
1	SOH	33	!	65	A	97	a
2	STX	34	”	66	B	98	b
3	ETX	35		67	C	99	c
4	EOT	36	$	68	D	100	d
5	ENQ	37	%	69	E	101	e
6	ACK	38	&	70	F	102	f
7	BEL	39	,	71	G	103	g
8	BS	40	(	72	H	104	h
9	HT	41	)	73	I	105	i
10	LF	42	*	74	J	106	j
11	VT	43	+	75	K	107	k
12	FF	44	,	76	L	108	l
13	CR	45	-	77	M	109	m
14	SO	46	.	78	N	110	n
15	SI	47	/	79	O	111	o
16	DLE	48	0	80	P	112	p
17	DCI	49	1	81	Q	113	q
18	DC2	50	2	82	R	114	r
19	DC3	51	3	83	X	115	s
20	DC4	52	4	84	T	116	t
21	NAK	53	5	85	U	117	u
22	SYN	54	6	86	V	118	v
23	TB	55	7	87	W	119	w
24	CAN	56	8	88	X	120	x
25	EM	57	9	89	Y	121	y
26	SUB	58	:	90	Z	122	z
27	ESC	59	;	91	[	123	{
28	FS	60	<	92	\	124	\|
29	GS	61	=	93	]	125	}
30	RS	62	>	94	^	126	~
31	US	63	?	95	—	127	DEL

The ASCII value is a decimal number, and the meaning of the control characters is as shown in the following table.

NUL empty	VT vertical tab	SYN idle synchronization
SOH Title Start	FF paper feed control	End of ETB message group transmission
STX text begins	CR carriage return	CAN void
ETX End of text	SO shift output	EM paper ends
EOY end of transmission	SI shift input	SUB substitution
ENQ query character	DLE space	ESC code escape
ACK acknowledge	DC1 Device Control 1	FS text separator
BEL alarm	DC2 Device Control 2	GS group separator
BS back one space	DC3 device control 3	RS record separator
HT horizontal list	DC4 Device Control 4	US unit separator
LF line feed	NAK negation	DEL delete

Since the number of characters in the standard ASCII character set is limited, it often cannot meet the requirements in practical applications. To this end, the International Organization for Standardization has formulated the ISO2022 standard, which stipulates a unified method for extending the ASCII character set to 8-bit codes while maintaining compatibility with ISO646. ISO has successively formulated a batch of extended ASCII character sets suitable for different regions. Each extended ASCII character set can be extended by 128 characters. The encoding of these extended characters is an 8-bit code with a high bit of 1 (that is, decimal numbers 128~255 ), called extended ASCII code.

Extended ASCII characters satisfy the need for more characters. Extended ASCII contains the 128 characters already in ASCII (numbers 0–32 are shown in the image below), plus an additional 128 characters for a total of 256.