4. Example of STL swap algorithm

• Template function calls normally ommit template parameters,
  because the typenames can be absorbed directly from the actual function call parameters.

• However, template parameters of functions may also be specified by the programmer:

  
      #include <cassert>
      #include <algorithm>
  
      using namespace std;
  
      int main (int argc, char* argv[])
      {
          int one = 1;
          int two = 2;
          swap< int >( one, two ); // explicit template param
          swap( one, two );        // implicit template param
          assert( one == 1 );
          assert( two == 2 );
          return 0;
      }
  
  

• Because swap expects both arguments to be of the same type, it needs only one template parameter.