copysign(x,y)函数详解

float copysign(float x, float y);
double copysign(double x, double y);
long double copysign(long double x, long double y);
promoted copysign(type1 x, type2 y);

#include <iostream>  
#include<math.h>  
using namespace std;  
int main()  
{  
    double x=15.9;  
    double y=9;  
    std::cout << "Values of x and y are: " <<x<<", "<<y<< std::endl;  
    cout<<"copysign(15.9,9) ="<<copysign(x,y);  
    return 0;  
}  

#include <iostream>  
#include<math.h>  
using namespace std;  
int main()  
{  
    double x=-8.6;  
    double y=-3.2;  
    std::cout << "Values of x and y are :" <<x<<" ,"<<y<< std::endl;  
    cout<<"copysign(-8.6,-3.2) ="<<copysign(x,y);  
    return 0;  
}