Can we have functions inside functions in C++?

Question

I mean something like:

int main() 
{
  void a() 
  {
      // code
  }
  a();

  return 0;
}

Answer 1

Local classes have already been mentioned, but here is a way to let them appear even more as local functions, using an operator() overload and an anonymous class:

int main() {
    struct {
        unsigned int operator() (unsigned int val) const {
            return val<=1 ? 1 : val*(*this)(val-1);
        }
    } fac;

    std::cout << fac(5) << '\n';
}

I don't advise on using this, it's just a funny trick (can do, but imho shouldn't).

---

2014 Update:

With the rise of C++11 a while back, you can now have local functions whose syntax is a little reminiscient of JavaScript:

auto fac = [] (unsigned int val) {
    return val*42;
};