?
Solved

Unable to understand while my while loop doesn't work (my first C exercise)

Posted on 2006-11-15
7
Medium Priority
?
221 Views
Last Modified: 2010-08-05
Hi.

Yes, a nb.
I have a problem with the following program I need to write as an essay.
assuming these are my variables:

startRange = 9
endRange = 20

I need to calculate which are the "powerfull" numbers, never mind what it means :)
the thing is that my while doesn't exit when it reaches the appropriate condition.

I am talking about the only while loop in this piece of code, so it won't be hard for you guys to find it :)

                  printf("Number : acceeding / powerfull\n");
                  for(currentNumber=startRange; currentNumber<=endRange; currentNumber++)
                  {
                        x=2;
                        while(currentNumber%x!=0 && x<currentNumber)
                        {
                              printf("%d",currentNumber);
                              printf("\n");
                              x++;
                        }
                  }
0
Comment
Question by:webiz
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
7 Comments
 
LVL 84

Expert Comment

by:ozo
ID: 17951658
It looks like the while loop does exit when currentNumber%x ==0 or x>= currentNumber
if that is not what you wanted, do you consider to be appropriate condition?
It may be hard for you to see what x is in the loop since you never print it.
0
 
LVL 1

Author Comment

by:webiz
ID: 17951746
well, it might look like it but it doesn't ;)
what I am getting is the following result:

9
11
11
11
11
11
11
11
11
11
13
13
13
13
13
13
13
13
13
13
13
15
17
17
17
17
17
17
17
17
17
17
17
17
17
17
17
and so on...

while I am supposed to get only
9
11
13
17
.....
0
 
LVL 84

Expert Comment

by:ozo
ID: 17951787
well when currentNumber is 11,  x will loop from 2 to 10, and then exit the loop when x=11 and && x<currentNumber fails
each time through the loop, you print currentNumber, so you print it 11-2 = 9 times

Why are you supposed to get 9 and not 15?
0
Technology Partners: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

 
LVL 2

Expert Comment

by:numansiddique
ID: 17953776
what do u mean by powerfull numbers. if we know what it means it will be better to understand the problem
0
 
LVL 84

Expert Comment

by:ozo
ID: 17953793
if you want powers of primes, then you should have included 16
0
 
LVL 22

Expert Comment

by:grg99
ID: 17954953
you're printing "currentnumber" in the loop, so you'll see that value repeated as many times as the loop goes around.

0
 
LVL 46

Accepted Solution

by:
Kent Olsen earned 1000 total points
ID: 17955360
Hi webiz,

This might be a little clearer if the inner loop is rewritten.

               printf("Number : acceeding / powerfull\n");
               for(currentNumber=startRange; currentNumber<=endRange; currentNumber++)
               {
                    for (x=2; currentNumber%x!=0 && x<currentNumber; x++)
                    {
                         printf("%d\n",currentNumber);
                    }
               }

This is the exact loop that you execute in your example.  Perhaps you really mean to do something like this:

               printf("Number : acceeding / powerfull\n");
               for(currentNumber=startRange; currentNumber<=endRange; currentNumber++)
               {
                    for (x=2; x<currentNumber; x++)
                    {
                         if (currentNumber % x != 0)
                         {
                           printf("%d\n",currentNumber);
                           break;
                         }
                    }
               }


Good Luck,
Kent
0

Featured Post

Independent Software Vendors: We Want Your Opinion

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Preface I don't like visual development tools that are supposed to write a program for me. Even if it is Xcode and I can use Interface Builder. Yes, it is a perfect tool and has helped me a lot, mainly, in the beginning, when my programs were small…
This tutorial is posted by Aaron Wojnowski, administrator at SDKExpert.net.  To view more iPhone tutorials, visit www.sdkexpert.net. This is a very simple tutorial on finding the user's current location easily. In this tutorial, you will learn ho…
The goal of this video is to provide viewers with basic examples to understand recursion in the C programming language.
Video by: Grant
The goal of this video is to provide viewers with basic examples to understand and use for-loops in the C programming language.
Suggested Courses
Course of the Month9 days, 11 hours left to enroll

762 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question