Functions returning void

C++ truths discusses an interesting interview question:

"Can you write a return statement in a function that returns void?" The answer is "Yes! You can return void!"

The following is a simple program picked up from the same blog and modified showing a function returning void

//Program tested on Microsoft Visual Studio 2008 - Zahid Ghadialy
//This is a simple example of a function returning void
#include<iostream>

using namespace std;

static void foo (void)
{
  cout<<"foo() called"<<endl;
}
static void bar (void)
{
  cout<<"bar() called"<<endl;
  return foo(); // Note this return statement.
}
int main ()
{
  cout<<"main() called"<<endl;
  bar();
  return 0;
}

The output is as follows:

This feature is very useful in case of Templates. Lets write a simple program that uses Templates:

//Program tested on Microsoft Visual Studio 2008 - Zahid Ghadialy
//This is a simple example of a Template returning void
#include<iostream>
//#include <typeinfo> - Some compilers may need this

using namespace std;

template <class T> T FOO (void)
{
  cout<<"T FOO() called with T = "<<typeid(T).name()<<endl;
  return T(); // Default construction
}

template <class T> T BAR (void)
{
  cout<<"T BAR() called with T = "<<typeid(T).name()<<endl;
  return FOO<T>(); // Syntactic consistency. Same for int, void and everything else.
}

int main (void)
{
  cout<<"main() called"<<endl;
  BAR<void>();
  BAR<int>();
  BAR<char>();
}

The output is as follows: