#include <cmath>
int function round(double num) {
  char sign = static_cast<char>(num/fabs(num));
  return static_cast<int>(sign* (fabs(num)+ 0.5));
}

Actually, the solution I gave first (and then suddenly changed it to the one that only works for positive number…) worked perfectly with both positive and negative too. This is it:

#include <cmath>
int function round(double num) {
  return static_cast<int>(floor(num+0.5));
}

I was a bit shocked first, finding out there was no round function in C++.

It didn't fortunately take me long to google a nice substitute for it. It can be as simple as this (Warning: this works for positive numbers only. See above for better solution):

int round(double num) {
 return (int)(num+0.5);
}

I may be one of the more dumb and lazy programmers (isn't „laziness“ in the flag of all programmers?), but I would expect a function like that to be a part of a modern language. Yes, it didn't take me long to google it (unlike some other C++ problems, which can take hours), but no googling is faster than short googling, isn't it?

I think it is worth seeing, what The Others offer