How can I round up decimal values in C++?

Question

If I have, for example, the number 9.83333 and I want to round it to 9.84 or 9.9. How can I do this?

Answer 1

There’s a function called std::round in the <cmath> header file that rounds a real number to the nearest integer. You can use that to round to the nearest tenth by computing std::round(10 * x) / 10.0, or to the nearest hundredth by calling std::round(100 * x) / 100.0. (Do you see why that works?)

You seem to be more interested in rounding up rather than rounding to the nearest value, which you can do by using the std::ceil function rather than std::round. However, the same basic techniques above still work for this.

Hope this helps!