有多少种显示小数的方法？

Question

So i was making a program to solve a math exercise (quadratic equation in english i think). The site's examples gave me 1.25 0 -1.25 and the output 1.00 and -1.00.

Made the program, but only got 5/100 (because only the "no root for the equation" worked). The problem was that the output didn't display .00 so i searched for a way to show decimals, when i stumbled across

std::cout.precision(2);
std::cout.setf(std::ios::fixed);

which worked and got 100/100.

So are there easier ways to do this? I'm a beginner at c++. If not, at least can somebody explain those 2 lines to me?

Answer 1

If you

#include <iomanip>

you can use:

std::cout << std::setprecision(2) << std::fixed << n;

Answer 2

I would go the long way and convert the floating point number to a string and make my own precision routines up. This is the problem in college and I would be making my own routines up. Using precision floating point was not in my beginning c++ class so you have to point to your reference of study. I got docked down because I knew too much for the simple class and did not reference my sources.