How can I round a double number in c++?

Question

Hi.
How can I round a number in c++? I'm using this code:
round(double * 100) / 100;
It works correctly. But sometimes I don't want this result. for example, sometimes the number has just 1 decimal digit (example: 1.8) and I want to see the result as 1.80. How can I do this?

Answer 1

You have to first set the output as fixed, then set the precision to 2 decimal places. Something like this:

double var = round(double * 100) / 100;
std::cout << std::fixed << std::setprecision(2) << var;

Unfortunately, it only works on the output stream. If you need the value for another computation, I don't know of any other way currently.

Answer 2

@nik1082
I don't think he can force the computer to calculate something using 1.80 as the computer will omit the zero in its calculations automatically. So it must be for output itself.