1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
|
#include <stdio.h>
/* The C Programming Language: 2nd Edition
*
* Exercise 4-14: Define a macro swap(t,x,y) that interchanges two arguments
* of type t. (Block structure will help.)
*
* Answer: Macros are read and processed before syntax is, so you can turn
* a macro into shorthand code; more shorthand than functions sometimes.
*
* This macro assumes x and y are of t type. If the types don't match up,
* it'll (probably) break.
*/
#define swap(t, x, y) {\
t z;\
z = x;\
x = y;\
y = z;\
}
int main() {
int a = 3;
int b = 7;
printf("a is %d, b is %d\n", a, b);
swap(int, a, b);
printf("Now swap, and... a is %d and b is %d!\n", a, b);
return 0;
}
|
