1 /*------------------------------------
2 binbit.c -- 使用位操作显示二进制
3 ------------------------------------*/
4
5 #include <stdio.h>
6 #include <limits.h> //提供 CHAR_BIT 的定义，CHAR_BIT 表示每字节的位数
7
8 char* itobs(int, char*);
9 void show_bstr(const char*);
10
11 int main()
12 {
13 char bin_str[CHAR_BIT * sizeof(int) + 1];
14 int number;
15
16 puts("Enter integers and see them in binary.");
17 puts("Non-numeric input terminates program");
18
19 while (scanf("%d", &number) == 1)
20 {
21 itobs(number, bin_str);
22
23 printf("%d is ", number);
24
25 show_bstr(bin_str);
26
27 putchar('\n');
28 }
29
30 puts("Bye");
31
32 return 0;
33 }
34
35 char* itobs(int n, char *ps)
36 {
37 const static int size = CHAR_BIT * sizeof(int);
38
39 for (int i(size - 1); i >= 0; --i, n >>= 1)
40 ps[i] = (01 & n) + '0';
41 ps[size] = '\0';
42
43 return ps;
44 }
45
46 //以4位为一组，显示二进制字符串
47 void show_bstr(const char *str)
48 {
49 int i = 0;
50 while (str[i]) //不是空字符
51 {
52 fputc(str[i], stdout);
53
54 if (++i % 4 == 0 && str[i])
55 fputc(' ', stdout);
56 }
57 }
