#include <iostream>
#include <iomanip>
using namespace std;
int main()
{
    double q =15.14259863;

    cout << showpoint       << q << endl;       //預設輸出六位有效數字
    cout << setprecision(3) << q << endl;       //定義輸出有效位數字
    cout << showpoint       << q  << endl;
    cout << setprecision(7) << q << endl;
    cout << showpoint       << q << endl;
    return 0;
}
 

#include<iostream>
#include<iomanip>
using namespace std;
int main()
{
    float i;
    double j;
    i = 10/3.0;
    j = 10/3.0;
    cout << fixed;               //讓浮點型固定以數字的方式顯示
    cout << setprecision(5);     //控制顯示的小數位數
    cout << i << "  " << endl;
    cout << setprecision(8);
    cout << j << "  " << endl;
    return 0;
}