Why can't I define a function inside another function?

Question

This is not a lambda function question, I know that I can assign a lambda to a variable.

What\'s the point of allowing us to declare, but not define a function insid

Answer 1

Specifically answering this question:

From the answers it seems that there in-code declaration may be able to prevent namespace pollution, what I was hoping to hear though is why the ability to declare functions has been allowed but the ability to define functions has been disallowed.

Because consider this code:

int main()
{
  int foo() {

    // Do something
    return 0;
  }
  return 0;
}

Questions for language designers:

1. Should foo() be available to other functions?
2. If so, what should be its name? int main(void)::foo()?
3. (Note that 2 would not be possible in C, the originator of C++)
4. If we want a local function, we already have a way - make it a static member of a locally-defined class. So should we add another syntactic method of achieving the same result? Why do that? Wouldn't it increase the maintenance burden of C++ compiler developers?
5. And so on...