How to prevent rounding error in c++?

Question

How I can prevent rounding error in C++ or fix it?

Example:

float SomeNumber = 999.9999;
cout << SomeNumber << endl;

It prints out 1000!

Answer 1

You can alter the rounding done by cout by setting the precision.

cout.precision(7);
float SomeNumber  = 999.9999;
cout << SomeNumber  << endl;

Alternatively, you can use printf from cstdio.