Thread: Nested while loop inside for loop

Guys I finished my assignment but while changing the variable names I think I messed something up and now the calculations are wrong and I seriously can't figure out what happened. For instance, when I enter in 15 for the first section and 30 for the second section, it should add them up to 45 and then divide them by 2 to get the school average but it messes that part up for some reason!

The program works fine all except for the calculations. If you run the program you'll see what i'm talking about.

Code:

#include <stdio.h>

int main(void)
{

int sCode, studID, m, loop = 0, loopS = 0;
float mark, totalPrint, totalStored, averageSection = 0, averageSchool = 0;


printf("\n\nEnter the Section Code: ");
scanf("%d", &sCode);
do{
  totalStored = 0;
  loopS++;

  while (sCode > 4 || sCode < 1)
  {
    printf("Invalid value entered. Must be 1 to 4, please re-enter: ");
    scanf("%d", &sCode);
  }
  
  printf("Enter the Student's ID: ");
  scanf("%d", &studID);
  do {
    totalPrint = 0;
    loop++;
  for (m = 1; m < 6; m++)
    {
      printf("Enter Mark #%d: ", m);
      scanf("%f", &mark);
      while (mark > 20 || mark < 0)
      {
        printf("Invalid grade entered. Must be 0.0 to 20.0, please re-enter: ");
        scanf("%f", &mark);
      }
      totalStored = totalStored + mark;
      totalPrint = totalPrint + mark;
      averageSection = (totalStored / (loop * 100)) * 100;
    }

    printf("%d's total mark is: %.2f\n", studID, totalPrint);
    printf("Enter the Student's ID ['0' to quit]: ");
    scanf("%d", &studID);
  } while (studID != 0);

averageSchool = (averageSchool + averageSection) / loopS;

printf("Enter the Section Code ['0' to quit]: ");
scanf("%d", &sCode);
printf("\nThe average for the section is: %.2f%\n\n", averageSection);
} while (sCode != 0);

printf("\nThe average for the course is: %.2f%\n\n", averageSchool);

}

Originally Posted by Sonny

Code:

  do {
    totalPrint = 0;
    loop++;
  for (m = 1; m < 6; m++)
    {
      printf("Enter Mark #%d: ", m);
      scanf("%f", &mark);
      while (mark > 20 || mark < 0)
      {
        printf("Invalid grade entered. Must be 0.0 to 20.0, please re-enter: ");
        scanf("%f", &mark);
      }
      totalStored = totalStored + mark;
      totalPrint = totalPrint + mark;
      averageSection = (totalStored / (loop * 100)) * 100;
    }

    printf("%d's total mark is: %.2f\n", studID, totalPrint);
    printf("Enter the Student's ID ['0' to quit]: ");
    scanf("%d", &studID);
  } while (studID != 0);

averageSchool = (averageSchool + averageSection) / loopS;

printf("Enter the Section Code ['0' to quit]: ");
scanf("%d", &sCode);
printf("\nThe average for the section is: %.2f%\n\n", averageSection);
} while (sCode != 0);

printf("\nThe average for the course is: %.2f%\n\n", averageSchool);

}

Your averageSection (in red) is being calculated for every students mark vice each section - which is what you want it to do. Now, if you don't want it to calculate over for each mark (aka each pass through your for loop) where would you put it?

Ok, I will give you a hint: You do not want the part in red to be in your for loop. Now you have a 50/50 chance on where you are going to put it. Pick one, try it out and see what happens.

Originally Posted by AndrewHunter

Ok, I will give you a hint: You do not want the part in red to be in your for loop. Now you have a 50/50 chance on where you are going to put it. Pick one, try it out and see what happens.

I have tried putting it everywhere, before the for loop after the for loop and the average for the school is still the same. :s

Are you sure it has something to do with the placement of;
averageSection = (totalStored / (loop * 100)) * 100;

No matter where I put it the final calculations are always messed up.

ok, look at your code and think about it:

1. Your for loop is for each student. So anything in your for loop should only be for the student. Just below that loop is the calculation for averages for the student.
2. Your inner do-while loop is for each section. So anything in that loop should be for the section. Just below that needs to be calulation for averages for the section.
3. Your outer do-while loop is for the school. Anything in that loop should be for the school. Just below that loop should be calculations for averages for the school.

So:

Code:

do{
     ask for section info
     do{
          ask for student info
          for student marks{
               get student marks
               maintain total for marks
          }
          calculate student average
          maintain section total
     }
     calculate section average
     maintain total school
}
calculate school average

Originally Posted by AndrewHunter

So:

Code:

do{
     ask for section info
     do{
          ask for student info
          for student marks{
               get student marks
               maintain total for marks
          }
          calculate student average
          maintain section total
     }
     calculate section average
     maintain total school
}
calculate school average

Code:

  do {
    totalPrint = 0;

    for (m = 1; m < 6; m++)
    {
      printf("Enter Mark #%d: ", m);
      scanf("%f", &mark);
      while (mark > 20 || mark < 0)
      {
        printf("Invalid grade entered. Must be 0.0 to 20.0, please re-enter: ");
        scanf("%f", &mark);
      }
      totalStored = totalStored + mark;
      totalPrint = totalPrint + mark;
	  
    }

    printf("%d's total mark is: %.2f\n", studID, totalPrint);
    printf("Enter the Student's ID ['0' to quit]: ");
    scanf("%d", &studID);
  
  } while (studID != 0);
  averageSection = (totalStored / (loop * 100)) * 100;


printf("Enter the Section Code ['0' to quit]: ");
scanf("%d", &sCode);
printf("\nThe average for the section is: %.2f%\n\n", averageSection);
} while (sCode != 0);
averageSchool = (averageSchool + averageSection) / loop;
printf("\nThe average for the course is: %.2f%\n\n", averageSchool);

I changed em to where you told me but still no luck.
Maybe if you could tell me what you meant by maintain total?

The outline I gave you was general. You need to reset your counters as well. Ok, you know what look at this. NOTE: I did not do percentages for this. I am sure you can figure out that math

Code:

#include <stdio.h>

int main(void)
{

	int sCode, studID, m, loop = 0, loopS = 0;
	float mark, totalPrint, totalStored, totalSchool=0,averageSection = 0, averageSchool = 0;


	printf("\n\nEnter the Section Code: ");
	scanf("%d", &sCode);
	do{
		totalStored = 0;
		averageSection = 0;
		loop = 0;
		loopS++;

		while (sCode > 4 || sCode < 1){
			printf("Invalid value entered. Must be 1 to 4, please re-enter: ");
			scanf("%d", &sCode);
		}
  
		printf("Enter the Student's ID: ");
		scanf("%d", &studID);
		do{
			totalPrint = 0;
			loop++;
			for (m = 1; m < 6; m++){
				printf("Enter Mark #%d: ", m);
				scanf("%f", &mark);
				while (mark > 20 || mark < 0){
					printf("Invalid grade entered. Must be 0.0 to 20.0, please re-enter: ");
					scanf("%f", &mark);
				}
				totalPrint = totalPrint + mark;
			}
			totalStored = totalStored + totalPrint;
			printf("%d's total mark is: %.2f\n", studID, totalPrint);
			printf("Enter the Student's ID ['0' to quit]: ");
			scanf("%d", &studID);
		} while (studID != 0);
		
		averageSection = (totalStored / loop);
		totalSchool = totalSchool + averageSection;
		printf("\nThe average for the section is: %.2f%\n\n", averageSection);
		
		printf("Enter the Section Code ['0' to quit]: ");
		scanf("%d", &sCode);

	} while (sCode != 0);
	
	averageSchool = (totalSchool / loopS);
	printf("\nThe average for the course is: %.2f%\n\n", averageSchool);

	
	return (0);
}

Sonny ... Stop Guessing!

It looks for all the world like as soon as you have the slightest problem, you just start randomly bumbling around trying stuff without even knowing why you're trying it... This is not going to work!

When things go wrong stop and THINK about it, work out what's wrong and why... Then create a solution.

As we've told you at least a dozen times... you cannot solve a problem you do not understand. The key here is to take the time to understand... don't just start screwing with your code.

Originally Posted by Sonny

I know dude haha, i've been trying to figure out what's wrong for over 3 hours now and my assignment is due tomorrow. I'm stressing out right now no time to go through it and plan it out again. :P

You don't have to... Go back to your original plan, look at your code... figure out where your mistake is, then fix it.

I GUARAN-DARN-TEE that if you spend 5 minutes thinking it through, you'll save yourself hours of making even more mistakes....

I once new an RC Modeler who would get so far into a project, make a mistake, trash it and start over. He didn't have the first clue about trouble-shooting. My cousin, also an avid RC Pilot, took a half dozen of this guy's "failed projects" home and after minor repairs, he flew every one of them!

As the back cover of the Hitchiker's Guide To The Galaxy says: Don't Panic!.