指针变量作为参数改变变量的值

[c]代码库

int main(){
   void exchange(int* p1, int* p2, int* p3);
   int a, b, c, *p1, *p2, *p3;
   scanf("%d%d%d", &a, &b, &c);
   p1 = &a;
   p2 = &b;
   p3 = &c;
   exchange(p1, p2, p3);
   printf("order in descend:%d %d %d\n", a, b, c);
   return 0;
}

void swap(int *p1, int* p2);

void exchange(int* p1, int* p2, int* p3){//简单选择排序思想
   if(*p1 < *p2) swap(p1, p2);
   if(*p1 < *p3) swap(p1, p3);
   if(*p2 < *p3) swap(p2, p3);
}

void swap(int* p1,int* p2){
   int p;
   p = *p1;
   *p1 = *p2;
   *p2 = p;
}