More Rand Issues

[Orangejuice]

Hello all, I recently posted a thread concerning issues with using rand in programs.

I am still having some trouble as I now have to change the program again.

The program outputs 4 problems for the user to complete and displays a congratulatory message if the user got the answer correct, as well as giving a message telling the user if they got it wrong and gives them another chance at the problem until they get it right.

Now I need the program to output 20 problems with not only random integers between 10-99, but I also need it to give a random operand between *,/,+,-.

Here is the program now:

#include <iostream>
#include <cstdlib>
#include <time.h>
#include <iomanip>

using namespace std;

int main()
{
    srand(time(NULL));

    double a = rand()%(99-10+1) + 10;
    double b = rand()%(99-10+1) + 10;
    double c = rand()%(99-10+1) + 10;
    double d = rand()%(99-10+1) + 10;
    double e = rand()%(99-10+1) + 10;
    double f = rand()%(99-10+1) + 10;
    double g = rand()%(99-10+1) + 10;
    double h = rand()%(99-10+1) + 10;

    double value_1, value_2, value_3, value_4;

    static const char* answers[] = {"\nNice Job!\n\n" , "\nCongratulations! Your answer is correct.\n\n", "\nYes! You are right!\n\n"};

    cout<< "This program will test your arithmetic skills.\n \n";

    cout<<"  "<<a<<"+"<<b<< " = ";
    cin>>value_1;

        while (value_1 != (a+b))
        {
            cout<< "Sorry, wrong answer. Please try to enter the correct answer again. \n\n";
            cout<< "  "<<a<<"+"<<b<< " = ";
            cin>> value_1;
        }

        if (value_1 == (a+b))
        {
            cout << answers[rand() % 3];
        }

    cout<<"  "<<c<<"-"<<d<< " = ";
    cin>>value_2;

        while (value_2 != (c-d))
        {
            cout<< "Sorry, wrong answer. Please try to enter the correct answer again. \n\n";
            cout<< "  "<<c<<"-"<<d<< " = ";
            cin>> value_2;
        }

        if (value_2 == (c-d))
        {
        cout << answers[rand() % 3];
        }

    cout<<"  "<<e<<"*"<<f<< " = ";
    cin>>value_3;

        while (value_3 != (e*f))
        {
            cout<< "Sorry, wrong answer. Please try to enter the correct answer again. \n\n";
            cout<< "  "<<e<<"*"<<f<< " = ";
            cin>> value_3;
        }

        if (value_3 == (e*f))
        {
            cout << answers[rand() % 3];
        }

    cout<<"  "<<g<<"/"<<h<< " = ";
    cin>>value_4;

        while (value_4 <= (g/h)-.01 || value_4 >= (g/h)+.01)
        {
            cout<< "Sorry, wrong answer. Please try to enter the correct answer again. \n\n";
            cout<< "  "<<g<<"/"<<h<< " = ";
            cin>> value_4;
        }

        if (value_4 >= (g/h)-.009 && value_4 <= (g/h)+.009)
        {
            cout << answers[rand() % 3];
        }

    return 0;
}

Can you use rand to choose between 4 options that are not integers? Or is there a way I can use rand to choose between integers that are assigned to each individual operand?

Finally, Is there a way I can just use a and b as my variables and have them be assigned different numbers each time they are used instead of using 40 different variables like a,b,c,d,e....

[ResidentBiscuit]

rand()%(99-10+1) + 10; Why this? Why are you having the computer calculate this over and over?

Operators:
You can enumerate them. Basically it's a name that gets assigned a number, you can then check the number and output the correspond operand for that.

Operands:
Break this into functions and I think you'll see the solution is pretty simple

[Albatross]

I think the OP did it to remember the range of the values the rands could emit. Any decent optimizing compiler will precompute the value for him. :)

@OP:
1. Yes you can, you'll just have to have some sort of mapping from one to the other. I would, as ResidentBiscuit suggested, use functions.
2. Yes. Just do the assignment each time you need to change them (ex. line 41).

-Albatross

[Orangejuice]

Thanks for your help ResidentBiscuit and Albatross!

I think the program works the way it should now. I have tested the program a few times and I have yet to find any issues.

So here's the code I came up with:

#include <iostream>
#include <cstdlib>
#include <time.h>
#include <iomanip>

using namespace std;


void Problems ();
double value;

int main()
{
    srand(time(NULL));
    cout<< "This program will test your arithmetic skills.\n \n";
    int Problem_Number = 1;
    while (Problem_Number<=20)
    {
    Problem_Number++;
    Problems();
    }


    return 0;
}

void Problems()
{
    static const char* answers[] =
    {"\nNice Job!\n\n" , "\nCongratulations! Your answer is correct.\n\n", "\nYes! You are right!\n\n"};

        double a = rand()%(99-10+1) + 10;
        double b = rand()%(99-10+1) + 10;
        double op = rand()%(4-1+1) + 1;
        double value1,value2;

        if (op==1)
        {
            value1 = a+b;

            cout<<a<<"+"<<b<<" = ";
            cin>>value2;
            while (value1 != value2)
            {
                cout<< "Sorry, wrong answer. Please try to enter the correct answer again. \n\n";
                cout<< "  "<<a<<"+"<<b<< " = ";
                cin>>value2;
            }
            if (value2 = value1)
            {
                cout << answers[rand() % 3];
            }

        }
        else if (op==2)
        {
            value1 = a-b;

            cout<<a<<"-"<<b<<" = ";
            cin>>value2;
            while (value1 != value2)
            {
                cout<< "Sorry, wrong answer. Please try to enter the correct answer again. \n\n";
                cout<< "  "<<a<<"-"<<b<< " = ";
                cin>>value2;
            }
            if (value2 == value1)
            {
                cout << answers[rand() % 3];
            }
        }
        else if (op==3)
        {
            value1 = a*b;

            cout<<a<<"*"<<b<<" = ";
            cin>>value2;
            while (value1 != value2)
            {
                cout<< "Sorry, wrong answer. Please try to enter the correct answer again. \n\n";
                cout<< "  "<<a<<"*"<<b<< " = ";
                cin>>value2;
            }
            if (value2 = value1)
            {
                cout << answers[rand() % 3];
            }
        }
        else
        {
            value1 = a/b;

            cout<<a<<"/"<<b<<" = ";
            cin>>value2;
            while (value2 <= (a/b)-.01 || value2 >= (a/b)+.01)
            {
                cout<< "Sorry, wrong answer. Please try to enter the correct answer again. \n\n";
                cout<< "  "<<a<<"/"<<b<< " = ";
                cin>>value2;
            }
            if (value2 >= (a/b)-.01 && value2 <= (a/b)+.01)
            {
                cout << answers[rand() % 3];
            }
        }
}

Please don't hesitate to tell me what I could have done better or more efficiently, or if there are problems I did not detect in the program.

Also @ ResidentBiscuit - How could I get my computer to not calculate that over and over again while still generating random variables in that range?

[ResidentBiscuit]

Well, that whole bit in the parentheses could be brought to just one number.