Question

Rewrite the C++ code below so the the following conditions are met:

• You may create any number of classes.
• You may edit the main() function.
• Remove the variable string type completely from the entire program. -- Note: Entire program includes all classes, all functions, and main().
• Get rid of every if and if else statement completely from the entire program. -- Note: Entire program includes all classes, all functions, and main().

Hint: Use polymorphism.

#include <iostream>
#include <vector>
#include <algorithm>
#include <numeric>
using namespace std;

class ArrayFunction {
public:
    ArrayFunction(const string& type) {
        this->type = type; 
    }

    float calculate(float array[], int size) {
        if (type == "mean") {
            float sum = accumulate(array, array + size, 0.0); 
            return sum / size;
        }
        else if (type == "min") {
            return *min_element(array, array+size);
        }
        else if (type == "max") {
            return *max_element(array, array+size);
        }
        else if (type == "first") {
            return array[0];
        }
        return 0;
    }

private:
    string type;
};

int main() {
    float array[] {1,2,3,7};
    vector<ArrayFunction*> functions;
    functions.push_back(new ArrayFunction("mean"));
    functions.push_back(new ArrayFunction("min"));
    functions.push_back(new ArrayFunction("max"));
    functions.push_back(new ArrayFunction("first"));

    for (int i = 0; i < functions.size(); i++) {
        cout << functions[i]->calculate(array, 4) << endl;
        delete functions[i];
    }

    return 0;
}

Example output:

3.25
1
7
1

Answer 1

program logic:

• We are going to define to define four different classes:
  • 1.) arrayMean: This will be a parent class. In this calculate() function will be virtual and will return the mean of elemets in array
  • 2.) arrayMax: this will inherit arrayMean. calculate() function wil be overriden to calcualte maximum value in array
  • 3.) arrayMin: this will inherit arrayMean. calcualte() function will be overrriden to calcullate mimimum value in array
  • 4.) arrarFirst: this will inherit from arrayMean. calculate() funciton will be overriden to find first value in array
• In main(), functions vector will be of type arrayMean*. We will be able to store all its subclass types in the vector.

program:

#include <iostream>
#include <vector>
#include <algorithm>
#include <numeric>
using namespace std;

class ArrayMean {
public:
   
virtual float calculate(float array[], int size) {
float sum = accumulate(array, array + size, 0.0);
return sum / size;
}
};
class ArrayMin: public ArrayMean {
public:
   
float calculate(float array[], int size) override {

return *min_element(array, array+size);
  
}
};

class ArrayMax: public ArrayMean {
public:
   
float calculate(float array[], int size) override {
return *max_element(array, array+size);

}
};

class ArrayFirst: public ArrayMean {
public:
float calculate(float array[], int size) override {
return array[0];
}
};
int main() {
float array[] {1,2,3,7};
vector<ArrayMean*> functions;
functions.push_back(new ArrayMean());
functions.push_back(new ArrayMin());
functions.push_back(new ArrayMax());
functions.push_back(new ArrayFirst());

for (int i = 0; i < functions.size(); i++) {
cout << functions[i]->calculate(array, 4) << endl;
delete functions[i];
}

return 0;
}

output:

3.25 1 7 1