C++设置精度

新手学习C++并且不理解我尝试使用 setprecision（2） 的问题，说 setprecision（2） 是未定义的。如果有人能帮忙，我将不胜感激。

 #include <iostream>     
 #include <string>
using namespace std;
int main() 
{
double price,shipping;
cout<<"Enter total price of of the order: "<<endl;
cin>>price;
if(price > 75) 
    shipping = 0;
else if(price > 50) 
    shipping = 5;
else if(price > 25)
    shipping = 10;
else if(price > 0)
    shipping = 15;
cout<<"Total price of order including shipping is: "<<fixed<<setprecision(2)
    <<price + shipping<<endl;


return 0;
system("pause");
}