Thread: Simple Error

When I compile this, is gives me this error: C:\Documents and Settings\Brandon\Desktop\C++ Folder\final\Cpp1.cpp(38) : error C2297: '%' : illegal, right operand has type 'double' . I have the error commented below inside of the int GetRandomNumber() function, but I simpy have no idea how to fix it. Any help will be greatly appreciated.

Code:

#include <iostream.h>
#include <iomanip.h>
#include <math.h>
#include <stdlib.h>
#include <time.h>

int  GetRandomNumber();
void ProgramDescription();
void Menu();
void Addition();
void Subtraction();
void Multiplication();
void CorrectResponse(int t);
void AskPlayAgain(bool & play);

const double low = -20;
const double high = 20;
const int LOOP_LIMIT = 10;

void main()
{
	bool play;

	srand(time(0));

	ProgramDescription();
	do{
		Menu();
		AskPlayAgain(play);
	}while (play==true);
}


//ERROR
int GetRandomNumber()
{
	srand(time(0));
	//ERROR IS HERE 
                return low + rand()%(high - low + 1);
}

void ProgramDescription()
{
	cout << "This program will give a student ten questions of their choice:\n";
	cout << "Addition, Subtraction, and Multiplication.\n";
	cout << "Welcome to the Math Wizard.";
}

void Menu()
{
	int option;
	cout << "Menu\n";
	cout << "----\n";
	cout << "1 - Addition\n";
	cout << "2 - Subtraction\n";
	cout << "3 - Multiplication\n";
	cin  >> option;

	while (option != 1 && option != 2 && option != 3)
	{
		cout << "Please pick option 1 - 3.\n";
	}
	if (option == 1)
	{
		Addition();
	}
	else if (option == 2)
	{
		Subtraction();
	}
	else if (option == 3)
	{
		Multiplication();
	}
}

void Addition()
{

	int response;
	int numbers;
	int something;
	int answer;
	int number_1;
	int number_2;
	int counter;

	for (numbers = 1; numbers = LOOP_LIMIT; numbers = counter + 1)
	{
		number_1 = GetRandomNumber();
		number_2 = GetRandomNumber();
		answer = number_1 + number_2;
		cout << number_1 << " + " << number_2 << " = ";
		cin  >> response;

		srand(time(0));
		while (response != answer)
		{
			something = 1 + rand() % (4 - 1 + 1);
			switch (something)
			{
			case 1 : cout << "Nope, try again.\n";
					 break;
			case 2 : cout << "That is incorrect.\n";
					 break;
			case 3 : cout << "Not quite.\n";
					 break;
			case 4 : cout << "Come on you can do it.\n";
					 break;
			}
			
		cout << "Please try again.\n";
		cin  >> response;
		}
		if(response == answer)
		{
			something = 1 + rand() % (4-1+1);
			switch (something)
			{
			case 1 : cout << "Good Job!\n";
					 break;
			case 2 : cout << "Excellent!\n";
					 break;
			case 3 : cout << "Very Good!\n";
					 break;
			case 4 : cout << "Your're Good!\n";
					 break;
			}
			cout << "You're ready for the next one.\n";
		}
	}
}

void Subtraction()
{

	int response;
	int numbers;
	int something;
	int answer;
	int number_1;
	int number_2;
	int counter;

	for (numbers = 1; numbers = LOOP_LIMIT; numbers = counter + 1)
	{
		number_1 = GetRandomNumber();
		number_2 = GetRandomNumber();
		answer = number_1 - number_2;
		cout << number_1 << " - " << number_2 << " = ";
		cin  >> response;

		srand(time(0));
		while (response != answer)
		{
			something = 1 + rand() % (4 - 1 + 1);
			switch (something)
			{
			case 1 : cout << "Nope, try again.\n";
					 break;
			case 2 : cout << "That is incorrect.\n";
					 break;
			case 3 : cout << "Not quite.\n";
					 break;
			case 4 : cout << "Come on you can do it.\n";
					 break;
			}
			
		cout << "Please try again.\n";
		cin  >> response;
		}
		if(response == answer)
		{
			something = 1 + rand() % (4-1+1);
			switch (something)
			{
			case 1 : cout << "Good Job!\n";
					 break;
			case 2 : cout << "Excellent!\n";
					 break;
			case 3 : cout << "Very Good!\n";
					 break;
			case 4 : cout << "Your're Good!\n";
					 break;
			}
			cout << "You're ready for the next one.\n";
		}
	}
}

void Multiplication()
{

	int response;
	int numbers;
	int something;
	int answer;
	int number_1;
	int number_2;
	int counter;

	for (numbers = 1; numbers = LOOP_LIMIT; numbers = counter + 1)
	{
		number_1 = GetRandomNumber();
		number_2 = GetRandomNumber();
		answer = number_1 * number_2;
		cout << number_1 << " * " << number_2 << " = ";
		cin  >> response;

		srand(time(0));
		while (response != answer)
		{
			something = 1 + rand() % (4 - 1 + 1);
			switch (something)
			{
			case 1 : cout << "Nope, try again.\n";
					 break;
			case 2 : cout << "That is incorrect.\n";
					 break;
			case 3 : cout << "Not quite.\n";
					 break;
			case 4 : cout << "Come on you can do it.\n";
					 break;
			}
			
		cout << "Please try again.\n";
		cin  >> response;
		}
		if(response == answer)
		{
			something = 1 + rand() % (4-1+1);
			switch (something)
			{
			case 1 : cout << "Good Job!\n";
					 break;
			case 2 : cout << "Excellent!\n";
					 break;
			case 3 : cout << "Very Good!\n";
					 break;
			case 4 : cout << "Your're Good!\n";
					 break;
			}
			cout << "You're ready for the next one.\n";
		}
	}
}

void AsPlayAgain(bool & play)
{
	char response;

	cout << "Do you want more problems? (y or n)";
	cin  >> response;

	while (response != 'y' && response != 'Y' && response != 'n' && response != 'N')
	{
		cout << "Please enter y or n.";
		cin  >> response;
	}
	if (response == 'y'  || response == 'Y')
	{
		play = true;
	}
	else
	{
		play = false;
	}
}

I checked the code, and the probelm was using the modulo on doubles. Just turn high and low into int's and it works more or less okay.

You should do a bit of searching (like in the FAQ's) about headers and the format of main though. You should use the standard headers (no more '.h', and you have to add a 'c' to a few of them), and main() must return an int. I had to make these changes to get it to compile, but take a close look at the modified code:

Code:

#include <iostream>
#include <iomanip>
#include <cmath>
#include <cstdlib>
#include <ctime>

using namespace std;

int  GetRandomNumber();
void ProgramDescription();
void Menu();
void Addition();
void Subtraction();
void Multiplication();
void CorrectResponse(int t);
void AskPlayAgain(bool & play);

const int low = -20;
const int high = 20;
const int LOOP_LIMIT = 10;

int main()
{
	bool play;

	srand(time(0));

	ProgramDescription();
	do{
		Menu();
		AskPlayAgain(play);
	}while (play==true);

        return 0;  // not strictly necessary, but never hurts to state it explicitly
}