ascii 码，在编程中起到至关重要的作用。之前忘记时，要么使用程序，要么搜索网页；
而在linux 中可以方便使用 manpage 查询，这是我没想到的，今天记录一下，很方便。
man ascii
https://man7.org/linux/man-pages/man7/ascii.7.html
ASCII(7) Linux Programmer's Manual ASCII(7) NAME top ascii - ASCII character set encoded in octal, decimal, and hexadecimal DESCRIPTION top ASCII is the American Standard Code for Information Interchange. It is a 7-bit code. Many 8-bit codes (e.g., ISO 8859-1) contain ASCII as their lower half. The international counterpart of ASCII is known as ISO 646-IRV. The following table contains the 128 ASCII characters. C program 'X' escapes are noted. │ Oct Dec Hex Char │ Oct Dec Hex Char ────────────────────────────────────────────┼─────────────────────────── 000 0 00 NUL ' ' (null character) │ 100 64 40 @ 001 1 01 SOH (start of heading) │ 101 65 41 A 002 2 02 STX (start of text) │ 102 66 42 B 003 3 03 ETX (end of text) │ 103 67 43 C 004 4 04 EOT (end of transmission) │ 104 68 44 D 005 5 05 ENQ (enquiry) │ 105 69 45 E 006 6 06 ACK (acknowledge) │ 106 70 46 F 007 7 07 BEL 'a' (bell) │ 107 71 47 G 010 8 08 BS '' (backspace) │ 110 72 48 H 011 9 09 HT ' ' (horizontal tab) │ 111 73 49 I 012 10 0A LF ' ' (new line) │ 112 74 4A J 013 11 0B VT 'v' (vertical tab) │ 113 75 4B K 014 12 0C FF 'f' (form feed) │ 114 76 4C L 015 13 0D CR ' ' (carriage ret) │ 115 77 4D M 016 14 0E SO (shift out) │ 116 78 4E N 017 15 0F SI (shift in) │ 117 79 4F O 020 16 10 DLE (data link escape) │ 120 80 50 P 021 17 11 DC1 (device control 1) │ 121 81 51 Q 022 18 12 DC2 (device control 2) │ 122 82 52 R 023 19 13 DC3 (device control 3) │ 123 83 53 S 024 20 14 DC4 (device control 4) │ 124 84 54 T 025 21 15 NAK (negative ack.) │ 125 85 55 U 026 22 16 SYN (synchronous idle) │ 126 86 56 V 027 23 17 ETB (end of trans. blk) │ 127 87 57 W 030 24 18 CAN (cancel) │ 130 88 58 X 031 25 19 EM (end of medium) │ 131 89 59 Y 032 26 1A SUB (substitute) │ 132 90 5A Z 033 27 1B ESC (escape) │ 133 91 5B [ 034 28 1C FS (file separator) │ 134 92 5C '\' 035 29 1D GS (group separator) │ 135 93 5D ] 036 30 1E RS (record separator) │ 136 94 5E ^ 037 31 1F US (unit separator) │ 137 95 5F _ 040 32 20 SPACE │ 140 96 60 ` 041 33 21 ! │ 141 97 61 a 042 34 22 " │ 142 98 62 b 043 35 23 # │ 143 99 63 c 044 36 24 $ │ 144 100 64 d 045 37 25 % │ 145 101 65 e 046 38 26 & │ 146 102 66 f 047 39 27 ' │ 147 103 67 g 050 40 28 ( │ 150 104 68 h 051 41 29 ) │ 151 105 69 i 052 42 2A * │ 152 106 6A j 053 43 2B + │ 153 107 6B k 054 44 2C , │ 154 108 6C l 055 45 2D - │ 155 109 6D m 056 46 2E . │ 156 110 6E n 057 47 2F / │ 157 111 6F o 060 48 30 0 │ 160 112 70 p 061 49 31 1 │ 161 113 71 q 062 50 32 2 │ 162 114 72 r 063 51 33 3 │ 163 115 73 s 064 52 34 4 │ 164 116 74 t 065 53 35 5 │ 165 117 75 u 066 54 36 6 │ 166 118 76 v 067 55 37 7 │ 167 119 77 w 070 56 38 8 │ 170 120 78 x 071 57 39 9 │ 171 121 79 y 072 58 3A : │ 172 122 7A z 073 59 3B ; │ 173 123 7B { 074 60 3C < │ 174 124 7C | 075 61 3D = │ 175 125 7D } 076 62 3E > │ 176 126 7E ~ 077 63 3F ? │ 177 127 7F DEL Tables For convenience, below are more compact tables in hex and decimal. 2 3 4 5 6 7 30 40 50 60 70 80 90 100 110 120 ------------- --------------------------------- 0: 0 @ P ` p 0: ( 2 < F P Z d n x 1: ! 1 A Q a q 1: ) 3 = G Q [ e o y 2: " 2 B R b r 2: * 4 > H R f p z 3: # 3 C S c s 3: ! + 5 ? I S ] g q { 4: $ 4 D T d t 4: " , 6 @ J T ^ h r | 5: % 5 E U e u 5: # - 7 A K U _ i s } 6: & 6 F V f v 6: $ . 8 B L V ` j t ~ 7: ' 7 G W g w 7: % / 9 C M W a k u DEL 8: ( 8 H X h x 8: & 0 : D N X b l v 9: ) 9 I Y i y 9: ' 1 ; E O Y c m w A: * : J Z j z B: + ; K [ k { C: , < L l | D: - = M ] m } E: . > N ^ n ~ F: / ? O _ o DEL NOTES top History An ascii manual page appeared in Version 7 of AT&T UNIX. On older terminals, the underscore code is displayed as a left arrow, called backarrow, the caret is displayed as an up-arrow and the vertical bar has a hole in the middle. Uppercase and lowercase characters differ by just one bit and the ASCII character 2 differs from the double quote by just one bit, too. That made it much easier to encode characters mechanically or with a non-microcontroller-based electronic keyboard and that pairing was found on old teletypes. The ASCII standard was published by the United States of America Standards Institute (USASI) in 1968.
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