C 实战练习题目47

 1 #include<stdio.h>
 2 #define exchange(a,b) { int t;t=a;a=b;b=t;}//注意放在一行里
 3 int main()
 4 {
 5     int x=10;
 6     int y=20;
 7     printf("x=%d; y=%dn",x,y);
 8     exchange(x,y);
 9     printf("x=%d; y=%dn",x,y);
10     return 0;
11 }

x=10; y=20
x=20; y=10