1 #include <stdio.h>
2
3 #define swap_macro_0(a, b) \
4 do { \
5 typeof(a) c; \
6 c = a; \
7 a = b; \
8 b = c; \
9 } while(0)
10
11 #define swap_macro_1(a, b) \
12 do { \
13 a = a + b; \
14 b = a - b; \
15 a = a - b; \
16 }while(0)
17
18 #define swap_macro_2(a, b) \
19 do { \
20 a = a ^ b; \
21 b = a ^ b; \
22 a = a ^ b; \
23 }while(0)
24
25 #define swap_macro_3(a, b) \
26 do { \
27 a = a * b; \
28 b = a / b; \
29 a = a / b; \
30 }while(0);
31
32 #define swap_macro_4(a, b) \
33 do { \
34 a = a + b - (b = a); \
35 }while(0);
36
37 int main()
38 {
39 int type, a, b;
40
41 scanf("%d, %d, %d", &type, &a, &b);
42 printf("before a = %d, b = %d\n", a, b);
43 switch(type)
44 {
45 case 0:
46 {
47 swap_macro_0(a, b);
48 break;
49 }
50 case 1:
51 {
52 swap_macro_1(a, b);
53 break;
54 }
55 case 2:
56 {
57 swap_macro_2(a, b);
58 break;
59 }
60 case 3:
61 {
62 swap_macro_3(a, b);
63 break;
64 }
65 case 4:
66 {
67 swap_macro_4(a, b);
68 break;
69 }
70 default:
71 {
72 printf("unknown swap type!\n");
73 return 0;
74 }
75 }
76 printf("after a = %d, b = %d\n", a, b);
77 return 0;
78 }
