計算機儲存的是二進位制，可以用8進位制，十進位制，16進位制進行表示，方便記錄與計算；
如何顯示符號？比如： 把a，b，c。。。 字母顯示出來，如何顯示？
這些字母在計算機儲存的二進位制是多少？它們是如何約定的。
為了解決上面的問題，C語言定義了ASCII碼錶：
//備註：0-32為控制字元，不可以列印
比如：
0=NULL 表示空
7=\a 表示響鈴一聲
8=\b 表示退格
10=\n 表示換行
12=\f 表示換頁
13=\r 表示enter回車
//
十進位制=16進位制=字元
33 = 0x21 = !
34 = 0x22 = "
35 = 0x23 = #
36 = 0x24 = $
37 = 0x25 = %
38 = 0x26 = &
39 = 0x27 = '
40 = 0x28 = (
41 = 0x29 = )
42 = 0x2a = *
43 = 0x2b = +
44 = 0x2c = ,
45 = 0x2d = -
46 = 0x2e = .
47 = 0x2f = /
48 = 0x30 = 0
49 = 0x31 = 1
50 = 0x32 = 2
51 = 0x33 = 3
52 = 0x34 = 4
53 = 0x35 = 5
54 = 0x36 = 6
55 = 0x37 = 7
56 = 0x38 = 8
57 = 0x39 = 9
58 = 0x3a = :
59 = 0x3b = ;
60 = 0x3c = <
61 = 0x3d = =
62 = 0x3e = >
63 = 0x3f = ?
64 = 0x40 = @
65 = 0x41 = A
66 = 0x42 = B
67 = 0x43 = C
68 = 0x44 = D
69 = 0x45 = E
70 = 0x46 = F
71 = 0x47 = G
72 = 0x48 = H
73 = 0x49 = I
74 = 0x4a = J
75 = 0x4b = K
76 = 0x4c = L
77 = 0x4d = M
78 = 0x4e = N
79 = 0x4f = O
80 = 0x50 = P
81 = 0x51 = Q
82 = 0x52 = R
83 = 0x53 = S
84 = 0x54 = T
85 = 0x55 = U
86 = 0x56 = V
87 = 0x57 = W
88 = 0x58 = X
89 = 0x59 = Y
90 = 0x5a = Z
91 = 0x5b = [
92 = 0x5c = \
93 = 0x5d = ]
94 = 0x5e = ^
95 = 0x5f = _
96 = 0x60 = `
97 = 0x61 = a
98 = 0x62 = b
99 = 0x63 = c
100 = 0x64 = d
101 = 0x65 = e
102 = 0x66 = f
103 = 0x67 = g
104 = 0x68 = h
105 = 0x69 = i
106 = 0x6a = j
107 = 0x6b = k
108 = 0x6c = l
109 = 0x6d = m
110 = 0x6e = n
111 = 0x6f = o
112 = 0x70 = p
113 = 0x71 = q
114 = 0x72 = r
115 = 0x73 = s
116 = 0x74 = t
117 = 0x75 = u
118 = 0x76 = v
119 = 0x77 = w
120 = 0x78 = x
121 = 0x79 = y
122 = 0x7a = z
123 = 0x7b = {
124 = 0x7c = |
125 = 0x7d = }
126 = 0x7e = ~
127 = 0x7f =
這樣螢幕就能把儲存為二進位制的字元資料，進行字元顯示
a-A= 97-65 =32
即可 a 比 A 大32； 透過增加32 個即可將大寫變成小寫
宣告：以上內容為 七里稻田 原創
如果需要檢視全課程 與 訓練題目，可以開啟如下連結：
http：//web。mashangyong。com/web/lcm/lcp#/lp/process/9
