Question

How do I modify the following function template so that it returns 42 if template parameters T and U are exactly the same type?

template<typename T,typename U>
int Foo()
{
  return 0;
}

Answer 1

Using std::is_same can provide the desired behaviour:

#include <type_traits>

template<typename T,typename U>
int Foo()
{
    return std::is_same<T, U>::value ? 42 : 0;
}