please help

[f1ddl3r]

i am very new to c++ and have grasped the concepts pretty well but im still struggling with a simple while loop. if someone could quickly proofread my work im sure it wont take longer than a moment. thanks.

// while loop inside of while loop
//

#include "stdafx.h"

#include <iostream>

using namespace std;
int main ()
{
	

	unsigned long int f;
		
	cout << "Give me a number up to 4294967295 \n";
	cin >> f;			
		
                while (f!= -1) {
			while (f>0) {
			cout << f << ",";	// shows number and adds a comma
			--f;			// subtracts one 
			}
			
			cout << "again?\n";
			cin >> f;
			
		} 
	}

	
	
		

	return 0;
}

thanks so much. i couldnt get much farther in c++ without learning this

[Ben Duncan]

You can knock off the firstwhile(f!=-1), as it is better portreyed in the second loop.

I also don't see the point of decrementing f.

[iwTf92yv]

@Duncan - there doesn't seem to be a point, it's just a while-loop-exercise that seems to be supposed to count backwards from the entered number to 1. The first while-statement seems to be the way to exit the program; if user enters "-1" instead of a new number, the program exits.

[hanst99]

Then make that an if statement. You are using it as one anyways.

[ascii]

Because f is an unsigned integer, it can't hold a negative value. However your first loop won't end until f hold the value of -1. This screws things up. Change the condition of your first while loop.

[f1ddl3r]

ok, so because its unsigned ive changed (f!=-1) to (f!=1) because that will still act the same way but im still getting errors.
what im really trying to do is have a loop that will count down but once it has reached zero the program will start over again without the need to restart it.
as dennisDOTcpp had said this is just a simple exercise and serves no purpose other than helping me to understand and get comfortable with loops.

[hanst99]

ok, so because its unsigned ive changed (f!=-1) to (f!=1) because that will still act the same way but im still getting errors.

-1 is not the same thing as 1. Where did you get your math education from?

[f1ddl3r]

i mean that it will do the same job. im not going to be counting down from 1 so instead i was hoping to use it now as my exit.

[ascii]

Okay, take a step back and explain to us, as clearly as you can, what you are trying to do, and what errors you are getting.

[f1ddl3r]

sorry. my specific goal is to have a program that will count down an input variable by one until it reaches 0. once it reaches 0 i want it to quit out of the while loop. but instead of having the program finished i would like it to still continue so that i can put in a new variable and have it count down that variable and then repeat. essentially i want to have the whole program to be a huge loop but the program in the huge loop is also nothing but a simple loop. is that helpful at all? sorry for the confusion

[ascii]

Yes. How is it that you want the program to end then? The way you explained it it sounds like you would just have to kill the process.

[chipp]

#include <iostream>

using namespace std;
int main ()
{
	

	unsigned long int f;
		
	cout << "Give me a number up to 4294967295 \n";
	cin >> f;			
	
	while (f>0) {
		cout << f << ",";	
		cout << "again?\n";
		cin >> f;
	}
	return 0;
}

this?

[novablows]

#include <iostream>

using namespace std;
int main ()
{
	

	unsigned long int f;
		
	cout << "Give me a number up to 4294967295 \n";
	
	 while(f==0){
		  cin >> f;
		    while (f>0){
		      f--;
		        cout <<f << "\n";}
	              cout << "again? \n";}
			         
			 
	return 0;
}

[f1ddl3r]

chipp - i was hoping to have the program count down such as put in 5 and the program will say

5,4,3,2,1, again?

and thenhave it so i can put in a new number and have it count down that number.

novablows- ive tried something similar to that and it only show the number once and then says

again?

[f1ddl3r]

I got it! novablows' skipped the loop because then my entry had to be zero but by making it while (f>=0) for the first loop it works great! thanks guys. i wouldnt be able to much farther in programming without loops haha. heres my final code:

// Testing.cpp : while loop in a while loop
//

#include "stdafx.h"

#include <iostream>

using namespace std;
int main ()
{
	

	unsigned long int f;
	cout << "\ngive me a number up to 4294967295 \n";
	cin >> f;

	while (f >= 0){
		while (f>0) {
			cout << f << ",";
			--f;
		}
		cout << "again?";
		cin >> f;
	}
		
		
		int wait;
	cin >> wait;
	return 0;
}

[ascii]

Awesome that you got it! I have a few other pieces of advice, however. On line 14, because the max int size can vary from computer to computer, I would recommend using the bitwise complement to figure out the maximum int size. Make sure it is unsigned. Changing the line to this:

cout << "\ngive me a number up to " << ~0U <<  endl;

will automatically adjust the number so that it shows the maximum int size on the specific computer. You could also use INT_MAX from climits to achieve the same effect: http://www.cplusplus.com/reference/clibrary/climits/

Also, you can combine lines 19 and lines 20 to make your code more concise like so:

cout << f-- << ",";

Lastly, instead of declaring the wait variable and using cin to read into it, you could just use getchar(), which will wait for the user to enter a character before exiting. Just my advice :)

[f1ddl3r]

ill get right on those things. any advice on not only getting my program to work but also on how to make it more technically correct is greatly appreciated. thanks!

[f1ddl3r]

alright so when i tried ~OU it didnt work. do i have to #define that? it did work for INT_MAX though.

[ne555]

use numeric_limits<unsigned int>::max() instead ( limits header )

unsigned int f;
while( f>= 0 ) // tautology 

[ascii]

Thats odd, the following program runs perfectly for me:

#include <iostream>

int main(void) {
    std::cout << ~0U << std::endl;
    return 0;
}