Homework help with looping

ms080tx · #1 20-Mar-2008, 18:25

Hi my assignment is simple I was to display a menu and then build functions that would do various things based on the user selection. my problem is I'm trying to have a do loop that will display the menu function display_menu until the q (quit opintion) is selected. What I want my loop to do is to is to keep displaying the menu function unitl q is selected then quite and exit the program. here are the area of codes I believe need some kind of fixing.

CPP / C++ / C Code:

char display_menu(void);

void main (void)
{
	
	do
	{
		display_menu();
	}
	while (display_menu() != 'Q' || display_menu() !='q');
		
	}
char display_menu (void)
 {
	int num1;
	int num2;
	char userchoice;
	

	cout << "Command Options\n---------------------------------------" << endl;
	cout << "a : Is sum even" << endl;
	cout << "b : sum between two integers" << endl;
	cout << "c : Prime" << endl;
	cout << "d : Reverse" << endl;
	cout << "q : Quit" << endl;
	cout << "Enter a command a,b,c or q" << endl;
	cin >> userchoice;
	
	switch (userchoice)
	{
	case 'a':
		cout << "Enter first number\t: ";
		cin >> num1;
		cout << "Enter second number\t: ";
		cin >> num2;
		cout << isEven(num1,num2); cout << endl;
		break;
	case 'b':
		cout << "Enter the first number for the sum between two integers : ";
		cin >> num1;
		cout << "Enter the second number for the sum between two integers : ";
		cin >> num2;
		sum(num1,num2); cout << endl ;
	
		break;
	case 'c' :
		cout << "Enter number : ";
		cin >> num1;
		isPrime(num1); cout << endl;
		break;
	case 'd' :
		cout << "Enter a positive number : ";
		cin >> num1;
		reverse(num1);cout << endl ;
		
		break;
	case 'q' :
		cout << "thank you come again" << endl;
		break;

	default :
		cout << "invalid choice";cout << endl;
		
	}
	return userchoice;

 }

I would like to solve my menu question using some kind of loop as basically all we have learned is loops and functions and simple operators. We are only about about half way or so in the semester for my programming class so try to keep it simple with any suggestions you may have. There are no compling errors but as I said before what is should be doing: displaying the menu unitl the user inputs q and then exiting the loop is not happening. Instead it cycles through the loop endless. Another quirky thing it does is that after entering Q
if on the next user entry is q is entered it will exit the program. Thank you for your time and help. to compile the program I'm using Microsoft visual studio 2005 on a windows XP o/s

C++_Bandit · #2 20-Mar-2008, 19:08

First off, do you have to use Microsoft Visual Studio 2005? If not then STOP, instead use either Code::Blocks or Bloodshed Dev C++ or any other free compiler.

Second, do you mind posting your entire code? I don't know how you're invoking the loop or getting the new choice.

ms080tx · #3 20-Mar-2008, 20:23

here is the entire code:

CPP / C++ / C Code:

/* HW 4
Tuesday lab 1:40 */
#include <iostream>
#include <iomanip>
#include <string>

using namespace std;
//prototype for functions
	bool isEven(int,int);
	int sum(int,int);
	bool isPrime(int);
	void reverse(int);
	char display_menu(void);

void main (void)
{
	
	do
	{
		display_menu();
	}
	while (display_menu() != 'Q' || display_menu() !='q');
		
	}
bool isEven (int number1, int number2)
{
	
	if ((number1 + number2)%2 ==0)
	{
		cout << " the sum of the numbers is even\t" << endl;
		return true; 
	}
	else 
	{
		cout << "the sum of the numbers is odd\t" << endl;
		return false;
	} 
		
	
}
 int sum (int number1, int number2)
 {
	 
	 int i,total=0;
	 
	if (number1>number2)
	 {
		for(i=number1; i >=number2; i--)
			total = total + i;
			cout << "sum of series is "<< total;
	 }
	else
	{
		for(i= number2; i >= number1; i--)
			total= total + i;
			cout << "sum of series is "<< total;
	}
	return total; 
 }
 bool isPrime(int number1)
 {
	if(number1== 2 || number1 == 3 || number1 == 5 || number1 == 7)
	{
		cout << "number is prime" << endl;
		return true;
	}
	else 
	{
		if ( number1%2== 0 || number1%3 == 0 || number1%5== 0 || number1%7== 0)
		{
			cout << "number is not prime" << endl;
			return false;
		}
		else 
		{
			cout << "number is prime" << endl;
			return true;
		}
	}
 }
 void reverse (int number1)
 {
	 if( number1 > 0 )
    {
        do
        {
            cout << (char)( '0' + (number1 % 10) );
            number1 /= 10;
        } while( number1 != 0 );
        cout << endl;
    }
	 else 
		 cout << "fool I said enter a positive number" << endl;

 }
 char display_menu (void)
 {
	int num1;
	int num2;
	char userchoice;
	

	cout << "Command Options\n---------------------------------------" << endl;
	cout << "a : Is sum even" << endl;
	cout << "b : sum between two integers" << endl;
	cout << "c : Prime" << endl;
	cout << "d : Reverse" << endl;
	cout << "q : Quit" << endl;
	cout << "Enter a command a,b,c or q" << endl;
	cin >> userchoice;
	
	switch (userchoice)
	{
	case 'a':
		cout << "Enter first number\t: ";
		cin >> num1;
		cout << "Enter second number\t: ";
		cin >> num2;
		cout << isEven(num1,num2); cout << endl;
		break;
	case 'b':
		cout << "Enter the first number for the sum between two integers : ";
		cin >> num1;
		cout << "Enter the second number for the sum between two integers : ";
		cin >> num2;
		sum(num1,num2); cout << endl ;
	
		break;
	case 'c' :
		cout << "Enter number : ";
		cin >> num1;
		isPrime(num1); cout << endl;
		break;
	case 'd' :
		cout << "Enter a positive number : ";
		cin >> num1;
		reverse(num1);cout << endl ;
		
		break;
	case 'q' :
		cout << "thank you come again" << endl;
		break;

	default :
		cout << "invalid choice";cout << endl;
		
	}
	return userchoice;

 }

Peter_APIIT · #4 21-Mar-2008, 03:23

Use int main instead of void because this is not a standard C++ code.

davekw7x · #5 21-Mar-2008, 13:47

Quote:

Originally Posted by ms080tx

here is the entire code:

Without looking at the functions other than main(), here's a suggestion:

In your loop, you should call the display_menu() once. Save its value to use as loop control.

Also look at the logic to decide when to continue: If the choice is not equal to 'Q' and the choice is not equal to 'q' you will continue.

So your version of main() could look like:

CPP / C++ / C Code:

int main(void)
{
    char choice;

    do 
    {
        choice = display_menu();
    }
    while (choice != 'Q' && choice != 'q');

    return 0;
}

Regards,

Dave

ms080tx · #6 21-Mar-2008, 17:53

thanks this seems to have fixed the problem!!!! that one little change from || to && and the few other changes fixed it. Thanks again for your help

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Homework help with looping

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