10进制转换成2、8、16进制の转换器

 1 #include <stdio.h>
 2 #include <limits.h>
 3 #include <math.h>
 4 #include <string.h>
 5 #include <stdlib.h>
 6 #include <ctype.h>
 7 int size;
 8 char string[CHAR_BIT * sizeof(int) + 1];
 9 void change_to_16(void)
10 {
11     printf("0x");
12     for (int j = 0, index = 0, count = 0, k = 0; j <size; j++, index++)
13     {
14         if (index == 0) count += (string[j] - ‘0‘) * 8;
15         if (index == 1) count += (string[j] - ‘0‘) * 4;
16         if (index == 2) count += (string[j] - ‘0‘) * 2;
17         if (index == 3)
18         {
19             count += (string[j] - ‘0‘);
20             if (count < 10) printf("%d", count);
21             else
22             {
23                 switch (count)
24                 {
25                 case 10:printf("a"); break;
26                 case 11:printf("b"); break;
27                 case 12:printf("c"); break;
28                 case 13:printf("d"); break;
29                 case 14:printf("e"); break;
30                 case 15:printf("f"); break;
31                 }
32             }
33             index = -1;
34             count = 0;
35         }
36     }
37 }
38 void change_to_8(void)
39 {
40     printf("0");
41     char string8[1000] = { 0 };
42     for (int j = size - 1, index = 0, count = 0, k = 0; j >= 0; j--, index++)
43     {
44         if (index == 0) count += string[j] - ‘0‘;
45         if (index == 1) count += (string[j] - ‘0‘) * 2;
46         if (index == 2)
47         {
48             count += (string[j] - ‘0‘) * 4;
49             string8[k++] = count + ‘0‘;
50             index = -1;
51             count = 0;
52         }
53     }
54     int len = strlen(string8);
55     for (int i = len - 1; i >= 0; i--)
56         printf("%c", string8[i]);
57 }
58 void change_to_2(void)
59 {
60     int j = 0;
61     while (string[j])
62     {
63         putchar(string[j]);
64         if (++j % 4 == 0 && string[j])
65             putchar(‘ ‘);
66     }
67 }
68 int main(void)
69 {
70     int number;
71     char button;
72     printf("choose the mode：\n");
73     printf("A,to binary\nB,to octal\nC,to hexadecimal\n");
74     scanf("%c", &button);
75     button = toupper(button);
76     fflush(stdin);
77     printf("Enter a decimal number:");
78     while (~scanf("%d", &number))
79     {
80         if (fabs(number) <= 15) size = 4;
81         else if (fabs(number) < 256&&fabs(number)>15) size = 8;
82         else if (fabs(number) >= 256 && fabs(number) < 4096) size = 12;
83         else if (fabs(number) >= 4096 && fabs(number) < 65536) size = 16;
84         else size = 20;
85         for (int i = size - 1; i >= 0; i--, number >>= 1)
86             string[i] = (01 & number) + ‘0‘;
87         string[size] = ‘\0‘;
88         switch (button)
89         {
90         case ‘A‘:change_to_2(); break;
91         case ‘B‘:change_to_8(); break;
92         case ‘C‘:change_to_16(); break;
93         }
94         putchar(‘\n‘);
95         printf("Enter a decimal number:");
96     }
97     return 0;
98 }