Templates and default arguments ...

template <typename genericType = int>
genericType add (genericType a, genericType b)
{
  return a + b;
}

int main ()
{
 int i1 = 1;
 double d2 = 3.14;
 
std::cout << "Add: " << add<> (i1,d2) << std::endl;

return 0;
}

test.cpp:14:27: error: no matching function for call to 'add'
  std::cout << "Add: " << add<> (i1,d2) << std::endl;
                          ^~~~~
test.cpp:4:13: note: candidate template ignored: deduced conflicting types for parameter 'genericType' ('int' vs. 'double')
genericType add (genericType a, genericType b)
            ^
1 error generated.

template <typename genericType = int>
genericType add (genericType a, genericType b)
{
  return a + b;
}

int main ()
{
 int i1 = 1;
 double d2 = 3.14;
 
std::cout << "Add: " << add<> (i1,d2) << std::endl;

return 0;
}