Template Class & Template Function – C++.

Template class help us to use generic classes and functions. Template allows a function or class to work on many different data types without being rewritten for each one. Instead of writing multiple overloaded function for the same purpose but with different data types we can use template class and do the same with a single function.

Function template

Function template : Function templates are special kind of functions that can operate with generic data types and this can be achieved using template parameters. A template parameter is a special kind of parameter that can be used to pass a type as argument as we do with regular function parameters. These function templates can use these parameters of different types to perform necessary routines.

The format for declaring function templates with type parameters is:

template <class list of identifiers>

function_declaration( template type identifier)

Example : Displaying different data types using Function Template

#include <iostream.h>

     template<class t1,class t2>

     void fun(t1 a,t2 b)

        {

             cout<<a<<”\t”<<b;

        }

     int main()

        {

             int x=4;

             float y=5.9;

             char z='S';

             fun(x,y); // <int,float>

             fun(y,z); // <float,char>

             fun(z,x); // <char,int>

             return 0;

        }

Example : Maximum of the two elements

#include <iostream.h>

     template <class T>

     T max(T a, T b)

        {

             return a > b ? a : b ;

        }

     void main()

        {

             int a,b;

             float x,y;

             char ch,ch1;

             cout<<"\n\tEnter two Integer Nos. : ";

             cin>>a>>b;

             cout<<"\n\tEnter two Real Nos. : ";

             cin>>x>>y;

             cout<<"\n\tEnter two Characters : ";

             cin>>ch>>ch1;

             cout<<"\n\n\tMaximum of "<<a<<" and "<<b<<" is = "<<max(a,b);

             cout<<"\n\n\tMaximum of "<<x<<" and "<<y<<" is = "<<max(x,y);

             cout<<"\n\n\tMaximum of "<<ch<<" and "<<ch1<<" is = "<<max(ch,ch1);

        }

Example : Swapping two elements

#include <iostream.h>

     template <class T>

     void swap(T &a, T &b)

        {

             T c;

             c=a;

             a=b;

             b=c;

        }

     void main()

        {

             int a,b;

             float x,y;

             char ch,ch1,*S,*S1;

             cout<<"\n\tEnter two Integer Nos. : ";

             cin>>a>>b;

             cout<<"\n\tEnter two Real Nos. : ";

             cin>>x>>y;

             cout<<"\n\tEnter two Characters : ";

             cin>>ch>>ch1;

             cout<<"\n\tEnter two Strin : ";

             cin>>S>>S1;

             cout<<"\n\n\tOrginal Input : "<<a<<","<<b;

             swap(a,b);

             cout<<" AfterSwap : "<<a<<","<<b;

             cout<<"\n\n\tOrginal Input : "<<x<<","<<y;

             swap(x,y);

             cout<<" AfterSwap : "<<x<<","<<y;

             cout<<"\n\n\tOrginal Input : "<<ch<<","<<ch1;

             swap(ch,ch1);

             cout<<" AfterSwap : "<<ch<<","<<ch1;

             cout<<"\n\n\tOrginal Input : "<<S<<","<<S1;

             swap(S,S1);

             cout<<" AfterSwap : "<<S<<","<<S1;

        }