(1)#include<cmath>而C语言是math.h
(2)交换两个指针的值
void exchange6_22(int *&p,int *&q)
{
int*c=p;
p=q;
q=c;
}
int main ()
{
int x=10,y=40;
int *p=&x;
int *q=&y;
cout<<p<<endl;
cout<<q<<endl;
exchange6_22(p,q);
cout<<p<<endl;
cout<<q<<endl;
system("pause");
return 0;
}