Question

Im reading c++ primer plus and having some issues understanding how implicit instantiation works. I havent learned classes yet, so I am just dealing with functions. I think I understand the basics of implicit instantiation (function templates) but I just dont understand explicit instantiation. I have below a function that uses a template, can someone show me how a function like this would be written if it used a explicit instantiation. You can change the way it works, but just keep it simple. I would really be appreciative. This will help me understand the syntax, and how it is used.

  2 #include <iostream>
  3 
  4 template <typename T>
  5 void show(T,T);
  6 
  7 
  8 int main()
  9 {
 10   int a = 10, b = 12;
 11   char c = 'x', d = 'y';
 12   
 13   show(a,b);
 14   show(c,d);
 15   
 16   return 0;
 17 } 
 18 
 19 template <typename T>
 20 void show(T a, T b )
 21 { 
 22   std::cout << "I used the int version " << a << " " << b << "\n";
 23 }

Answer 1

Just do a Show<int>(c, d) Notice that I’ve explicitly instantiated the int version, but passed the char parameters. That’s (a rather simple take on) explicit instantiation, but you might be actually referring to explicit specialization.