how to give ans exactly upto 15 decimal places in c++ code example

Example: how to print a decimal number upto 6 places of decimal in c++

#include <iostream>
#include <iomanip>

int main()
{
    double d = 122.345;

    std::cout << std::fixed;
    std::cout << std::setprecision(2);
    std::cout << d;
}