c++ function template code example

Example 1: c++ template function

template <class T>
void swap(T & lhs, T & rhs)
{
 T tmp = lhs;
 lhs = rhs;
 rhs = tmp;
}

Example 2: function template

template <class T>
void swap(T & lhs, T & rhs)
{
 T tmp = lhs;
 lhs = rhs;
 rhs = tmp;
}

void main()
{
  int a = 6;
  int b = 42;
  swap<int>(a, b);
  printf("a=%d, b=%d\n", a, b);
  
  // Implicit template parameter deduction
  double f = 5.5;
  double g = 42.0;
  swap(f, g);
  printf("f=%f, g=%f\n", f, g);
}

/*
Output:
a=42, b=6
f=42.0, g=5.5
*/

Example 3: template function in C++

// template specialization
#include <iostream>
using namespace std;

// class template:
template <class T>
class mycontainer {
    T element;
  public:
    mycontainer (T arg) {element=arg;}
    T increase () {return ++element;}
};

// class template specialization:
template <>
class mycontainer <char> {
    char element;
  public:
    mycontainer (char arg) {element=arg;}
    char uppercase ()
    {
      if ((element>='a')&&(element<='z'))
      element+='A'-'a';
      return element;
    }
};

int main () {
  mycontainer<int> myint (7);
  mycontainer<char> mychar ('j');
  cout << myint.increase() << endl;
  cout << mychar.uppercase() << endl;
  return 0;
}