Templates

Contents

Function Template Specialization

We defined a template function for general types but we want the function to behave differently for a particular type. We write a similar function with that type. This is known as Function Template Specialization.

File:: function1.cpp

#include <iostream>

using namespace std;


template <class T> T GetMax (T a1, T b1)
{
    T result;
    result = (a1>b1)? a1 : b1 ;
    cout << "Inside the template function." << endl ;
    return (result);
}

template <>
int GetMax<int> (int a1, int b1)
{
    int result;
    result = (a1>b1)? a1 : b1 ;
    cout << "Inside the int function." << endl ;
    return (result);
}



int main ()
{
    int i1=5, j1=6, k1;
    long l1=10, m1=5, n1;

    k1 = GetMax(i1, j1 );
    n1 = GetMax(l1, m1 );
    cout << k1 << endl;
    cout << n1 << endl;
    return 0;
}
$ g++ function1.cpp ; ./a.exe
Inside the int function.
Inside the template function.
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10

We can also add in a normal functions in addition to template specialization functions.

File:: function2.cpp

#include <iostream>

using namespace std;


template <class T> T GetMax (T a1, T b1)
{
    T result;
    result = (a1>b1)? a1 : b1 ;
    cout << "Inside the template function." << endl ;
    return (result);
}

template <>
int GetMax<int> (int a1, int b1)
{
    int result;
    result = (a1>b1)? a1 : b1 ;
    cout << "Inside the int function." << endl ;
    return (result);
}


int GetMax (int a1, int b1)
{
    int result;
    result = (a1>b1)? a1 : b1 ;
    cout << "Inside the overloaded function." << endl ;
    return (result);
}


int main ()
{
    int i1=5, j1=6, k1;
    long l1=10, m1=5, n1;

    k1 = GetMax(i1, j1 );
    n1 = GetMax(l1, m1 );
    cout << k1 << endl;
    cout << n1 << endl;
    return 0;
}
$ g++ function2.cpp ; ./a.exe
Inside the overloaded function.
Inside the template function.
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10

The compiler will consider the non-template function first to see if there is a match before moving on to template functions.

File:: template_ex1.cpp

#include <iostream>

using namespace std;

//TO DO
//Write a template function called Add
// that takes 2 arguments of the same type
// and returns a result using the "+" operator


int main ()
{
    int i1=5, j1=6  ;
    string str1 = "Charles  " ;
        string str2 = "Babbage" ;
    cout << Add(i1, j1) << endl;
    cout << Add(str1, str2) << endl;
    return 0;
}