C++ Adding an array

Question

I am new to C++ and am currently enrolled in an intro class. I am creating a program that is a programming tutorial (the irony!) and currently am trying to add a menu option that will take the user to a quiz. Nothing fancy. As of right now, it seems like my functions are not recognizing a class I created. Here's what I have so far, any (very dumbed down) advice would be most appreciated!

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

int main()
{
    string username = "";
    int choice;
    char c;
    char answer;
    int x = 4;
    int y = 5;
    int z = x + y;
    int ans;
    int total;
    
    class Question
    {
    private:
        string Question_Text;
        string Answer_one;
        string Answer_two;
        string Answer_three;

        int Correct_Answer;
        int Question_Score;

    public:
        void setValues(string, string, string, string, int, int);
        void askQuestion ( );
    };

    //welcome message
    cout << "Hello user, please enter your name:";
    cin >> username;
    cout << "Welcome to the programming tutorial " << username << "."<< endl;

    //menu selection
    while(toupper (choice != 'E'))
    {
        cout << "What would you like to do? (Unit 1 - Declaring Variables (1), Unit 2 - Input/ Output (2), Unit 3 - Conditionals (3), Quizzes (4) or Exit (E))";
        cin >> choice;
        if (choice == '1')
        {
            cout << "We will begin with defining variables. The first step to doing this is choosing which datatype your variable is.\n";
            cout << "The following are a few of the common datatypes used in programming.\n";
            cout << "Character ==> char\n";
            cout << "Integer ==> int, long, double\n";
            cout << "Boolean ==> bool\n";
            cout << endl;
            cout << "When declaring a variable, you must put its datatype before the variable name.\n";
            cout << "An example of this would be if we wanted to declare the value of x as 4.\n";
            cout << "We would write this as: \n";
            cout << "int x = 4\n";
            cout << "The program will now use the value 4 for the variable name 'x'\n";
            cout << endl;
            cout << "Now let's assume we assigned the value of 5 to the variable 'y'\n";
            cout << "If we wanted to add x and y and assign the sum to the variable 'z', we would write:\n";
            cout << "int z = x + y\n";
            cout << "Now when we use the variable 'z' in our program, it will perform the calculation given x=4 and y=5 and declare 9 as the value of the variable 'z'.\n";
            cout << "To test our code, we would write: " << endl;
            cout << "cout<<'x + y'<< z << endl; \n";
            cout << "If written correctly, it will display as: \n";
            cout << "x + y = " << z << "." << endl;
            
        }
        if (choice == '2')
        {
            cout << "Now that we understand the basics of declaring variables, let's discuss displaying, or output of, information to a user.\n";
            cout << "If you wanted to display a welcome message, for example, you would type:\n";
            cout << "cout << 'Welcome';\n";
            cout << "The line of code would start with 'cout' followed by two less than signs and then the message you wish to display in quotes.\n";
            cout << "Using this, you can ask the user for input.\n";
            cout << "Enter c to continue...";
            cin >> c;
            cout << "Let's say we have a program that flips a coin. You may want to ask the user how many times to flip the coin.\n";
            cout << "Assuming we previously declared this amount variable as 'int timesFlipped', we would 'cout' our question and the next line would read:\n";
            cout << "cin>> timesFlipped; \n";
            cout << "This will store the users input for the variable 'timesFlipped'\n";
            cout << "You almost always end a line of code with a semi colon."<<endl;
        }
        if (choice == '3')
        {
            cout << "This unit will cover conditional expressions."<<endl;
        }
        if (choice == '4')
        {
            string Question_Text;
            string Answer_one;
            string Answer_two;
            string Answer_three;

            int Correct_Answer;
            int Question_Score;
            Question q1;
            Question q2;
            Question q3;
        
            
            cout <<username << ", you have chosen to take a quiz." << endl << endl;
            int ans, score = 0;
            cout << "Unit One Quiz - Variables " << endl << endl;

            q1.setValues("How would you declare the value of 'x' as 12? ",
                "x=12()",
                "x==12()",
                "x=12;()",
                3,
                1);
            q2.setValues("What do you need to put before a variable when declaring it?",
                "a name()",
                "a value()",
                "a datatype()",
                3,
                1);
            q3.setValues("Which data type would you use for a number that includes a decimal value?",
                "int()",
                "double()",
                "float()",
                2,
                1);

            q1.askQuestion();
            q2.askQuestion();
            q3.askQuestion();
            
            cout << "Your score out of a possible 3 is " << total << endl;

        }
        if (choice == 'E')
        {
            cout << "Have a good day!";
            break;
        }
    }


    system("pause");
}

void Question :: setValues(string q, string a1, string a2, string a3, int ca, int pa)
{
    string Question_Text;
    string Answer_one;
    string Answer_two;
    string Answer_three;

    int Correct_Answer;
    int Question_Score;
    
    Question_Text = q;
    Answer_one = a1;
    Answer_two = a2;
    Answer_three = a3;
    Correct_Answer = ca;
    Question_Score = pa;
}

void Question :: askQuestion()
{
    string Question_Text;
    string Answer_one;
    string Answer_two;
    string Answer_three;

    int Correct_Answer;
    int Question_Score;
    int ans;
    int Total;

    cout << endl;
    cout << Question_Text << endl;
    cout << "1. " << Answer_one << endl;
    cout << "2. " << Answer_two << endl;
    cout << "3. " << Answer_three << endl << endl;
    cout << "Please enter your answer: " << endl;
    cin >> ans;

    if (ans == Correct_Answer)
    {
        cout << "That is correct!" << endl;
        Total = Total + Question_Score;
    }
    else
    {
        cout << "Sorry, that is incorrect" << endl;
        cout << "The correct answer was " << Correct_Answer << endl;
    }
}

I declared the variables in both functions because it wasn't recognizing them in each until I did so, but now i'm thinking it is because the class isn't being recognized.

Answer 1

Your program, for the purposes of the problem you're experiencing, can be whittled down into the following:

int main() 
{
    class Question  {
    public:
        void askQuestion();
    };

    Question q;
    q.askQuestion();
}

void Question::askQuestion() { }

You would get an error in the definition of Question::askQuestion(), since the class is declared (and defined) within the scope of the main() function - as is not recognized outside of it.

Move the class outside of main(), like so:

class Question  {
public:
    void askQuestion();
};

int main() 
{
    // you can use the Question class here, even though you haven't
    // defined all of its methods yet!
    Question q;
    q.askQuestion();
}

void Question::askQuestion() { }

... and this program does compile (godbolt.org).

That's not all, however... you're declaring your member variables (e.g. Question_text) inside each of your member functions. The local definition masks the class member, so you're only setting a local variable of your method, which gets destroyed when execution completes.

---

Other notes and suggestions:

• No need to use the word Question again in a method name, if the class already has it. i.e. Question::ask() seems like a better choice of name than Question::askQuestion(). Same goes for Question::Question_text.
• It's better to avoid using namespace std, and only using the classes, types or functions from std:: which you specifically intend to refer to.
• If you think about it, your use of the Question class is rather artificial. Its code is mostly the code for giving the quiz, rather than of a question-as-such, a question-unto-itself. It seems like a better choice of "object" would be a set of answers-and-values, or question parameters. Setting the values can be done by constructing a QuestionParameters object, and asking the question could be a function that takes such an object.
• If you have Answer_one, Answer_two, Answer_three - then you probably need a container, instead, e.g. std::vector<std::string> answers. You can then use an answer index instead of using if or switch statements.

Answer 2

Changes you must make to define the class outside of the main function Use the switch instead of if Use the int value instead of E to exit the program. I made changes to the code as follows

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

class Question
{
private:
    string Question_Text;
    string Answer_one;
    string Answer_two;
    string Answer_three;

    int Correct_Answer;
    int Question_Score;

public:
    void setValues(string, string, string, string, int, int);
    void askQuestion();
}; //end of class

//---------------------------
void Question ::askQuestion()
{
    string Question_Text;
    string Answer_one;
    string Answer_two;
    string Answer_three;

    int Correct_Answer;
    int Question_Score;
    int ans;
    int Total;

    cout << endl;
    cout << Question_Text << endl;
    cout << "1. " << Answer_one << endl;
    cout << "2. " << Answer_two << endl;
    cout << "3. " << Answer_three << endl
         << endl;
    cout << "Please enter your answer: " << endl;
    cin >> ans;

    if (ans == Correct_Answer)
    {
        cout << "That is correct!" << endl;
        Total = Total + Question_Score;
    }
    else
    {
        cout << "Sorry, that is incorrect" << endl;
        cout << "The correct answer was " << Correct_Answer << endl;
    }
} //end of askQuestion
//----------------------------------
void Question ::setValues(string q, string a1, string a2, string a3, int ca, int pa)
{
    string Question_Text;
    string Answer_one;
    string Answer_two;
    string Answer_three;

    int Correct_Answer;
    int Question_Score;

    Question_Text = q;
    Answer_one = a1;
    Answer_two = a2;
    Answer_three = a3;
    Correct_Answer = ca;
    Question_Score = pa;
} //end of setValues
//----------------------------------

int main()
{
    string username = "";
    int choice;
    char c;
    char answer;
    int x = 4;
    int y = 5;
    int z = x + y;
    int ans;
    int total;

    //welcome message
    cout << "Hello user, please enter your name:";
    cin >> username;
    cout << "Welcome to the programming tutorial " << username << "." << endl;

    //menu selection

    while (choice != 5)
    {
        cout << "What would you like to do? (Unit 1 - Declaring Variables (1), Unit 2 - Input/ Output (2), Unit 3 - Conditionals (3), Quizzes (4) or Exit (5))";
        cin >> choice;

        switch (choice)
        {
        case 1:
        {
            cout << "We will begin with defining variables. The first step to doing this is choosing which datatype your variable is.\n";
            cout << "The following are a few of the common datatypes used in programming.\n";
            cout << "Character ==> char\n";
            cout << "Integer ==> int, long, double\n";
            cout << "Boolean ==> bool\n";
            cout << endl;
            cout << "When declaring a variable, you must put its datatype before the variable name.\n";
            cout << "An example of this would be if we wanted to declare the value of x as 4.\n";
            cout << "We would write this as: \n";
            cout << "int x = 4\n";
            cout << "The program will now use the value 4 for the variable name 'x'\n";
            cout << endl;
            cout << "Now let's assume we assigned the value of 5 to the variable 'y'\n";
            cout << "If we wanted to add x and y and assign the sum to the variable 'z', we would write:\n";
            cout << "int z = x + y\n";
            cout << "Now when we use the variable 'z' in our program, it will perform the calculation given x=4 and y=5 and declare 9 as the value of the variable 'z'.\n";
            cout << "To test our code, we would write: " << endl;
            cout << "cout<<'x + y'<< z << endl; \n";
            cout << "If written correctly, it will display as: \n";
            cout << "x + y = " << z << "." << endl;
            break;
        }

        case 2:
        {
            cout << "Now that we understand the basics of declaring variables, let's discuss displaying, or output of, information to a user.\n";
            cout << "If you wanted to display a welcome message, for example, you would type:\n";
            cout << "cout << 'Welcome';\n";
            cout << "The line of code would start with 'cout' followed by two less than signs and then the message you wish to display in quotes.\n";
            cout << "Using this, you can ask the user for input.\n";
            cout << "Enter c to continue...";
            cin >> c;
            cout << "Let's say we have a program that flips a coin. You may want to ask the user how many times to flip the coin.\n";
            cout << "Assuming we previously declared this amount variable as 'int timesFlipped', we would 'cout' our question and the next line would read:\n";
            cout << "cin>> timesFlipped; \n";
            cout << "This will store the users input for the variable 'timesFlipped'\n";
            cout << "You almost always end a line of code with a semi colon." << endl;
            break;
        }
        case 3:
            cout << "This unit will cover conditional expressions." << endl;
            break;
        case 4:
        {
            string Question_Text;
            string Answer_one;
            string Answer_two;
            string Answer_three;

            int Correct_Answer;
            int Question_Score;
            Question q1;
            Question q2;
            Question q3;

            cout << username << ", you have chosen to take a quiz." << endl
                 << endl;
            int ans, score = 0;
            cout << "Unit One Quiz - Variables " << endl
                 << endl;

            q1.setValues("How would you declare the value of 'x' as 12? ",
                         "x=12()",
                         "x==12()",
                         "x=12;()",
                         3,
                         1);
            q2.setValues("What do you need to put before a variable when declaring it?",
                         "a name()",
                         "a value()",
                         "a datatype()",
                         3,
                         1);
            q3.setValues("Which data type would you use for a number that includes a decimal value?",
                         "int()",
                         "double()",
                         "float()",
                         2,
                         1);

            q1.askQuestion();
            q2.askQuestion();
            q3.askQuestion();
            cout << "Your score out of a possible 3 is " << total << endl;
            break;
        }

        case 5:
            cout << "Have a good day!";
            break;
        } //end of switch
    } //end of while

    system("pause");

    return 0;
} //end of main