Lesson 15 of 20Object-Oriented C++25 min

Templates and Generic Programming

Templates let one function or class work with several data types. The compiler creates the required version when the template is used.

Function Template

Generic maximum function

#include <iostream>
#include <string>
using namespace std;

template <typename T>
T larger(T a, T b)
{
    return (a > b) ? a : b;
}

int main()
{
    cout << larger(10, 20) << endl;
    cout << larger(4.5, 3.2) << endl;
    cout << larger(string("Apple"), string("Banana")) << endl;

    return 0;
}

Class Template

Generic Box class

template <typename T>
class Box
{
private:
    T value;

public:
    explicit Box(T newValue) : value(newValue) {}

    T getValue() const
    {
        return value;
    }
};

Where You Already Use Templates

STL types such as vector<int>, vector<string>, and unique_ptr<Student> are template-based types.

Practice task

Write a function template named smallest that returns the smaller of two values.

Lesson Summary

Write functions and classes that work with more than one data type.