Sample task and Solution : class template c++ of hackerrank

 You are given a main function which reads the enumeration values for two different types as input, then prints out the corresponding enumeration names. Write a class template that can provide the names of the enumeration values for both types. If the enumeration value is not valid, then print unknown.

Input Format

The first line contains , the number of test cases.
Each of the  subsequent lines contains two space-separated integers. The first integer is a color value, , and the second integer is a fruit value, .

Constraints

Output Format

The locked stub code in your editor prints  lines containing the color name and the fruit name corresponding to the input enumeration index.

Sample Input

2
1 0
3 3

Sample Output

green apple
unknown unknown

Explanation

Since , there are two lines of output.

1. The two input index values,  and , correspond to green in the color enumeration and apple in the fruit enumeration. Thus, we print green apple.
2. The two input values,  and , are outside of the range of our enums. Thus, we print unknown unknown.

Solution

#include <iostream>

using namespace std;

enum class Fruit { apple, orange, pear };

enum class Color { red, green, orange };

template <typename T> struct Traits;

// Define specializations for the Traits class template here.

template <>

struct Traits<Fruit>

{

public:

    static const char* name(int index) {

        Fruit f = (Fruit)index;

        switch (f)

        {

            case Fruit::apple:  return "apple";

            case Fruit::orange: return "orange";

            case Fruit::pear:   return "pear";

        }

        return "unknown";

    }

};

   

template <>

struct Traits<Color>

{

public:

    static const char* name(int index) {

        Color c = (Color)index;

        switch (c)

        {

            case Color::red:    return "red";

            case Color::green:  return "green";

            case Color::orange: return "orange";

        }

        return "unknown";

    }

};

int main()

{

    int t = 0; std::cin >> t;

    for (int i=0; i!=t; ++i) {

        int index1; std::cin >> index1;

        int index2; std::cin >> index2;

        cout << Traits<Color>::name(index1) << " ";

        cout << Traits<Fruit>::name(index2) << "\n";

    }

}

Source : HackerRank