Programming Forums > Application Development > C++

a3orange · Apr 12th, 2006, 4:59 PM

Hi, I'm testing a math problem for school,and I have a problem with the program I wrote to test it. Here is the [math] problem:

Joe has a deck of 100 cards. Each one has one yellow side, and one red side and each one is numbered from 1 to 100. All cards start with yellow facing up. He then turns around any cards that have a number divisible by 2. He does this for all numbers up to 100. How many cards have their yellow faces up at the end of this process?

Here is the code:

(Toggle Plain Text)

#include <iostream>
#include <string>
using namespace std;
const int decksize = 100;
int main()
{
	string cards[decksize] = "Yellow";
	int divby;
	for (divby == 2; divby < decksize; divby++)
	{
        int i;
		for (i = 0; i < decksize; i++)
		{
			if (cards[i] == "Yellow" && (i + 100) % divby == 0)
			{
				cards[i] = "Red";
			}
			else if (cards[i] == "Red" && (i + 100) % divby == 0)
			{
				cards[i] == "Yellow";
			}
		}
	}
int yellow;
int red;	
int n;
	for (n = 0; n < decksize; n++)
	{
		if (cards[n] == "Red")
		red++;
		else if (cards[n] == "Yellow")
		yellow++;
	}
cout << "Yellow: " << yellow << endl;
cout << "Red: " << red << endl;
cin.get();
cin.get();
return 0;
}

The program always crashes at this line:

(Toggle Plain Text)

if (cards[i] == "Yellow" && (i + 100) % divby == 0)

OpenLoop · Apr 12th, 2006, 5:15 PM

your definition of cards is inaccurate. You define it as a 100 element array of strings, and then you initialize it to one string.
What's the error you're getting?

Bench · Apr 12th, 2006, 5:18 PM

(Toggle Plain Text)

	int divby;
	for (divby == 2; divby < decksize; divby++)

look carefully at that line..

InfoGeek · Apr 12th, 2006, 8:02 PM

Quote:

How many cards have their yellow faces up at the end of this process?

50. No need to write the program. :p

OpenLoop · Apr 12th, 2006, 8:47 PM

man InfoGeek, my company sure can use a man like you. Can you compute the resulting balance of 3,500,000 policies after 6,000,000+ transactions a day? Let me know so we can return the mainframes back to IBM

a3orange · Apr 12th, 2006, 8:53 PM

OpenLoop:

Doesn't that make all elements of the array strings?

Thank you, bench, but the program is really messed up now, it returns the results:

Yellow: 121
Red: -2056523657

Infogeek:

I'm eventually going to make the program so the user can enter in the amount of cards and how high 'divby' goes. Also, I'm going to make it so there can be more then 2 colord on each of the cards. Maybe I'll make them pyramids.

OpenLoop · Apr 12th, 2006, 9:14 PM

string cards[10] <== this defines ten consecutive strings
char cards[10] <== this here is ten consecutive characters that can be called a string
string card <== this is one string

now, in your case, you're comparing cards[i] for a string. My guess is, you want an array where each element is a string. That would be the first case above.

EDIT: maybe that's what you need:

(Toggle Plain Text)

string cards[] = {"Yellow","Red","Green","Black"};

a3orange · Apr 12th, 2006, 9:26 PM

OpenLoop:

Didn't I already do that with:

(Toggle Plain Text)

string cards[decksize] = "Yellow";

Maybe I need to add curly braces around "Yellow"?

The Dark · Apr 12th, 2006, 9:31 PM

(Toggle Plain Text)

int yellow;
int red;	
int n;
	for (n = 0; n < decksize; n++)
	{
		if (cards[n] == "Red")
		red++;
		else if (cards[n] == "Yellow")
		yellow++;
	}

You need to give the yellow and red variables an initial value. At the moment they are just getting whatever value is in memory at the time.

The Dark · Apr 12th, 2006, 9:34 PM

Quote:

Originally Posted by a3orange

OpenLoop:

Didn't I already do that with:

(Toggle Plain Text)

string cards[decksize] = "Yellow";

Maybe I need to add curly braces around "Yellow"?

It is still only one value of "Yellow" that you are trying to assign into an array of values.
Try something like:

(Toggle Plain Text)

string cards[decksize];
for (int i = 0; i < decksize; i++)
  cards[i] = "Yellow";

Apr 12th, 2006, 4:59 PM	#1
a3orange Newbie Join Date: Apr 2006 Posts: 14 Rep Power: 0	Need Help With A Program Hi, I'm testing a math problem for school,and I have a problem with the program I wrote to test it. Here is the [math] problem: Joe has a deck of 100 cards. Each one has one yellow side, and one red side and each one is numbered from 1 to 100. All cards start with yellow facing up. He then turns around any cards that have a number divisible by 2. He does this for all numbers up to 100. How many cards have their yellow faces up at the end of this process? Here is the code: (Toggle Plain Text) #include <iostream> #include <string> using namespace std; const int decksize = 100; int main() { string cards[decksize] = "Yellow"; int divby; for (divby == 2; divby < decksize; divby++) { int i; for (i = 0; i < decksize; i++) { if (cards[i] == "Yellow" && (i + 100) % divby == 0) { cards[i] = "Red"; } else if (cards[i] == "Red" && (i + 100) % divby == 0) { cards[i] == "Yellow"; } } } int yellow; int red; int n; for (n = 0; n < decksize; n++) { if (cards[n] == "Red") red++; else if (cards[n] == "Yellow") yellow++; } cout << "Yellow: " << yellow << endl; cout << "Red: " << red << endl; cin.get(); cin.get(); return 0; } #include <iostream> #include <string> using namespace std; const int decksize = 100; int main() { string cards[decksize] = "Yellow"; int divby; for (divby == 2; divby < decksize; divby++) { int i; for (i = 0; i < decksize; i++) { if (cards[i] == "Yellow" && (i + 100) % divby == 0) { cards[i] = "Red"; } else if (cards[i] == "Red" && (i + 100) % divby == 0) { cards[i] == "Yellow"; } } } int yellow; int red; int n; for (n = 0; n < decksize; n++) { if (cards[n] == "Red") red++; else if (cards[n] == "Yellow") yellow++; } cout << "Yellow: " << yellow << endl; cout << "Red: " << red << endl; cin.get(); cin.get(); return 0; } The program always crashes at this line: (Toggle Plain Text) if (cards[i] == "Yellow" && (i + 100) % divby == 0) if (cards[i] == "Yellow" && (i + 100) % divby == 0)

Apr 12th, 2006, 5:18 PM	#3
Bench Newbie Join Date: Feb 2006 Posts: 20 Rep Power: 0	(Toggle Plain Text) int divby; for (divby == 2; divby < decksize; divby++) int divby; for (divby == 2; divby < decksize; divby++) look carefully at that line..

Apr 12th, 2006, 9:14 PM	#7
OpenLoop Expert Programmer Join Date: May 2005 Location: East Lansing, MI Posts: 663 Rep Power: 4	string cards[10] <== this defines ten consecutive strings char cards[10] <== this here is ten consecutive characters that can be called a string string card <== this is one string now, in your case, you're comparing cards[i] for a string. My guess is, you want an array where each element is a string. That would be the first case above. EDIT: maybe that's what you need: (Toggle Plain Text) string cards[] = {"Yellow","Red","Green","Black"}; string cards[] = {"Yellow","Red","Green","Black"};

Apr 12th, 2006, 9:26 PM	#8
a3orange Newbie Join Date: Apr 2006 Posts: 14 Rep Power: 0	OpenLoop: Didn't I already do that with: (Toggle Plain Text) string cards[decksize] = "Yellow"; string cards[decksize] = "Yellow"; Maybe I need to add curly braces around "Yellow"?

Apr 12th, 2006, 9:31 PM	#9
The Dark Expert Programmer Join Date: Jun 2005 Posts: 825 Rep Power: 4	(Toggle Plain Text) int yellow; int red; int n; for (n = 0; n < decksize; n++) { if (cards[n] == "Red") red++; else if (cards[n] == "Yellow") yellow++; } int yellow; int red; int n; for (n = 0; n < decksize; n++) { if (cards[n] == "Red") red++; else if (cards[n] == "Yellow") yellow++; } You need to give the yellow and red variables an initial value. At the moment they are just getting whatever value is in memory at the time.

Apr 12th, 2006, 5:15 PM	#2
OpenLoop Expert Programmer Join Date: May 2005 Location: East Lansing, MI Posts: 663 Rep Power: 4	your definition of cards is inaccurate. You define it as a 100 element array of strings, and then you initialize it to one string. What's the error you're getting?

Apr 12th, 2006, 8:47 PM	#5
OpenLoop Expert Programmer Join Date: May 2005 Location: East Lansing, MI Posts: 663 Rep Power: 4	man InfoGeek, my company sure can use a man like you. Can you compute the resulting balance of 3,500,000 policies after 6,000,000+ transactions a day? Let me know so we can return the mainframes back to IBM

Apr 12th, 2006, 8:53 PM	#6
a3orange Newbie Join Date: Apr 2006 Posts: 14 Rep Power: 0	OpenLoop: Doesn't that make all elements of the array strings? Thank you, bench, but the program is really messed up now, it returns the results: Yellow: 121 Red: -2056523657 Infogeek: I'm eventually going to make the program so the user can enter in the amount of cards and how high 'divby' goes. Also, I'm going to make it so there can be more then 2 colord on each of the cards. Maybe I'll make them pyramids.

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Programming Forums > Application Development > C++

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