[SOLVED] Keep Getting Segmentation Fault

MrxNine · 04-23-2011, 11:14 PM

Ok I need help. My program compiles and reads in from the datafile. The problem is that the input turns out as this:

Code:

Student     |Exam  0 |Exam  1 |Exam  2 |Exam  3 | Std Avg
Student 5    |     0     1     2     3%6
Student 1   |   101  |   100  |   100  |   100  |   100
Student 2   |    91  |    90  |   100  |    90  |   192
Student 3   |    81  |    50  |    60  |    80  |   260
Student 4   |   101  |    50  |    30  |   100  |   330
Exam Avg    |
   422   |   422   |   422   |   422   |   495   |   495   |   495   |   495   |                                                                                                                        567   |   567   |   567   |   567   |   660   |   660   |   660   |   660   |                                                                                                                     Exam Median |   100  |   100  |   100  |   100  |    90  |    90  |    90  |                                                                                                                         90  |   100  |   100  |   100  |   100  |   100  |   100  |   100  |   100  |

Here's the code I am using

Code:

#include <stdio.h>
#include "constants.h"

extern void bubblesort(int[], int);

int main()
{

	int i,j;
	int above, below;
	int scores[NUMBERofSTUDENTS][EXAMSCORES];
	int grade[NUMBERofSTUDENTS],counts[101];
	int readValues[NUMBERofSTUDENTS][EXAMSCORES];
	int median[EXAMSCORES],meanExam[EXAMSCORES],meanStudent[NUMBERofSTUDENTS];
	int sum=0;
	
	for ( i = 0; i < NUMBERofSTUDENTS; i++)    
	{
		for(j=0; j<EXAMSCORES; j++)
		{
			scanf("%d",&scores[i][j]);	
		}
        }
	
   	for(i=0; i<EXAMSCORES; i++)
	{
		for(j=0; j<NUMBERofSTUDENTS; j++)
		{
			grade[j] = scores[j][i];
		}
		bubblesort(grade,NUMBERofSTUDENTS);
		median[i] = grade[NUMBERofSTUDENTS/2];
	}

	for(i=0; i<NUMBERofSTUDENTS; i++)
	{
		for(j=0; j<EXAMSCORES; j++)
		{
			sum+=scores[i][j];
		}
		meanStudent[i]= sum/EXAMSCORES;
	}
	for(i=0; i<EXAMSCORES; i++)
	{
		for(j=0; j<NUMBERofSTUDENTS; j++)
		{
			sum+=scores[j][i];
		}
		meanExam[i]= sum/NUMBERofSTUDENTS;
	} 
		
	for(i = 0; i<EXAMSCORES; i++)
    	{
		for(j=0; j<NUMBERofSTUDENTS; j++)
		{
			counts[scores[j][i]++];
		}
		
		printf("Student     |");
		for(i=0; i<EXAMSCORES; i++)
		{
			printf("Exam  %-2d|",i);
		}
		printf(" Std Avg\n");
		printf("Student %d    |",j+1);

		for(i=0;i<EXAMSCORES; i++)
		{
		printf("%6d",i);
		}
		printf("%6\n",meanExam[i]);

	for(i=0;i<NUMBERofSTUDENTS;i++)
	{
		printf("Student %-4d|",i+1);
		for(j=0;j<EXAMSCORES;j++)
		{
			printf("%6d  |",scores[i][j]);
		}
		printf("%6d\n",meanStudent[i]);
	}

	printf("Exam Avg    |\n");
	for(i=0;i<EXAMSCORES;i++)
	{
		for(j=0;j<NUMBERofSTUDENTS;j++)
		printf("%6d   |", meanExam[i]);
	}

	printf("Exam Median |");
	for(i=0;i<EXAMSCORES;i++)
	{
		for(j=0;j<NUMBERofSTUDENTS;j++)
		printf("%6d  |", median[i]);
	}
}

Help?

dwhitney67 · 04-24-2011, 06:44 AM

Look here:

Code:

printf("%6\n",meanExam[i]);

What's missing from the format statement?

johnsfine · 04-24-2011, 07:30 AM

Quote:

Originally Posted by MrxNine

Help?

You seem to have ignored most of the help you already received in this thread.

In the first post you had

Quote:

counts[scores[j][i]]++;

Initially that was the line that was crashing. In post 9, that crash was explained, and the explanation clearly indicated a problem elsewhere, so no reason to change the crashing line. But now you have

Quote:

counts[scores[j][i]++];

What did you expect to accomplish with that change?

Earlier I wrote

Quote:

Originally Posted by johnsfine

it appears that you assume the array counts[] has been initialized to zeroes. Local variables in C don't work that way. If you want it initialized, your code needs to do that.

You made no change for that problem.

I also wrote.

Quote:

Originally Posted by johnsfine

take a closer look at all your uses of the variable sum. You are not doing what you intend.

You don't seem to have tried to fix that problem.

Since the code you posted doesn't have balancing braces (and so won't compile) I don't know how to relate it to the output you posted from some version that obviously did compile. But both the code and the output show the consequences of what you did to the loop starting at line 51.

I assume some editing accident removed the end of that loop and made unrelated following loops part of it. Then you adjusted the indenting to be consistent with the braces to make it seem like those other loops were intended to be nested. But look at the loops you nested there. Obviously nesting them was not correct.

MTK358 · 04-24-2011, 08:07 AM

Maybe you should read some online tutorials about pointers and arrays in C and play around with that, and then get back to this project?

Sergei Steshenko · 04-24-2011, 02:13 PM

Quote:

Originally Posted by MrxNine

... Help?

Copy-paste here the command line you've used for compilation and screen output produced by it.

MrxNine · 04-24-2011, 05:06 PM

I'm glad I can finally say I finished it.

Code:

#include <stdio.h>
#include "constants.h"

extern void bubblesort(int[], int);

int main()
{

	int i,j;
	int above, below, exam;
	int scores[NUMBERofSTUDENTS][EXAMSCORES];
	int grade[NUMBERofSTUDENTS],counts[101];
	int median[EXAMSCORES],meanExam[EXAMSCORES],meanStudent[NUMBERofSTUDENTS];
	int sum=0;
	
	for (i =0;i<NUMBERofSTUDENTS;i++)    
	{
		for(j=0; j<EXAMSCORES; j++)
		{
			scanf("%d",&scores[i][j]);	
		}
        }
	
   	for(i=0;i<EXAMSCORES;i++)
	{
		for(j=0;j<NUMBERofSTUDENTS;j++)
		{
			grade[j] = scores[j][i];
		}
		bubblesort(grade,NUMBERofSTUDENTS);
		if(NUMBERofSTUDENTS%2==0)
			median[i] = (grade[NUMBERofSTUDENTS/2] + grade[NUMBERofSTUDENTS/2-1])/2;
		else
			median[i] = grade[NUMBERofSTUDENTS/2];
	}

	for(i=0; i<NUMBERofSTUDENTS; i++)
	{
		sum = 0;
		for(j=0; j<EXAMSCORES; j++)
		{
			sum+=scores[i][j];
		}
		meanStudent[i]= sum/EXAMSCORES;
	}
	for(i=0; i<EXAMSCORES; i++)
	{
		sum = 0;
		for(j=0; j<NUMBERofSTUDENTS; j++)
		{
			sum+=scores[j][i];
		}
		meanExam[i]= sum/NUMBERofSTUDENTS;
	} 
	
	
		printf("Student     |");
		for(i=0; i<EXAMSCORES; i++)
		{
			printf(" Exam  %-2d|",i+1);
		}
		printf(" Std Avg\n");

	for(i=0;i<NUMBERofSTUDENTS;i++)
	{
		printf("Student %-4d|",i+1);
		for(j=0;j<EXAMSCORES;j++)
		{
			printf("%6d   |",scores[i][j]);
		}
		printf("%6d\n",meanStudent[i]);
	}
	
	printf("\n");
	printf("Exam Avg    |");
	for(i=0;i<EXAMSCORES;i++)
	{
		printf("%6d   |", meanExam[i]);
	}
	printf("\n");

	printf("Exam Median |");
	for(i=0;i<EXAMSCORES;i++)
	{
		printf("%6d   |", median[i]);
	}
	printf("\n");
	printf("\n");
	
	printf("EXAM GRADE DISTRIBUTION:\n");
	for(exam=0;exam<EXAMSCORES;exam++)
	{
	for(i=0;i<101;i++)
        {
                counts[i]=0;
	 }	
		above=0;
		for(j=0; j<NUMBERofSTUDENTS; j++)
		{
			counts[scores[j][exam]]++;
		}

                printf("Exam %d:\n",exam+1);

		//above=0;		
		for(i=100; i>=0; i--)
		{
			if(counts[i]!=0)
			{	
				below = NUMBERofSTUDENTS-counts[i]-above;
				printf("Score %3d : %d - %d above, %d below\n",i,counts[i],above,below);
			}
			above+=counts[i];
		}
		printf("\n");
	}
}

Output:

Code:

Student     | Exam  1 | Exam  2 | Exam  3 | Std Avg
Student 1   |   100   |   100   |     5   |    68
Student 2   |   100   |    90   |    60   |    83
Student 3   |    90   |    90   |   100   |    93
Student 4   |   100   |   100   |   100   |   100
Student 5   |   100   |    47   |    22   |    56
Student 6   |   100   |    50   |    14   |    54

Exam Avg    |    98   |    79   |    50   |
Exam Median |   100   |    90   |    41   |

EXAM GRADE DISTRIBUTION:
Exam 1:
Score 100 : 5 - 0 above, 1 below
Score  90 : 1 - 5 above, 0 below

Exam 2:
Score 100 : 2 - 0 above, 4 below
Score  90 : 2 - 2 above, 2 below
Score  50 : 1 - 4 above, 1 below
Score  47 : 1 - 5 above, 0 below

Exam 3:
Score 100 : 2 - 0 above, 4 below
Score  60 : 1 - 2 above, 3 below
Score  22 : 1 - 3 above, 2 below
Score  14 : 1 - 4 above, 1 below
Score   5 : 1 - 5 above, 0 below

Thanks for those who helped me!

GVrooman · 04-24-2011, 11:32 PM

A nice job of perservering through adversity. A+