将浮点型数显示到小数点后6位,用的是ios_base::fixed和ios_base::floatfield
#include<iostream>
int main()
{
using namespace std;
cout.setf(ios_base::fixed,ios_base::floatfield);
float tub = 10.0 / 3.0;
double mint = 10.0 / 3.0;
const float million = 1.0e6;
cout << "tub = " << tub;
cout << ", a million tubs = " << million * tub;
cout << ",\nand ten million tubs = ";
cout << 10 * million * tub << endl;
cout << "mint = " << mint << " and a million mints = ";
cout << million * mint << endl;
return 0;
}