Why this app not accepting setprecision

Answer 1

#include <iostream>
#include <iomanip>

// ...

std::cout << std::fixed << std::setprecision (your desired precision);

// ... do stuff

Answer 2

Works just fine for me. You might have to post your code for inspection.

Answer 3

You don't show code so I'm just guessing, but you may need to #include <iomanip>