Thread: Getting a segmentation fault.

Hello,

Still working on the same project if you have seen me post before.
Almost finished though. I'm working on the project where I have to take files that have multiple lines that look like this....

Tuesday,17
Wednesday,57
Friday,27
Tuesday,17

Anyways I have to see how many times each day is in each file. And I have to add up the number by that particular day.

Tested code and it ran smoothly the first file, but then gives me a segmentation fault the next time it tries to run one. I'm assuming that's me messing up on the pointers or something of the sort.
Any help would be great.
Thanks

Here's my code...

Btw it's the same loop twice. One is for the first 9 files, then the other one is for all of the double digit files.
Also I'm working on changing the counters to array's as we speak.

Code:

#include <stdio.h>#include <stdlib.h>


 
int main(void)
 {
     int day1total = 0;
     int day2total = 0;
     int day3total = 0;
     int day4total = 0;
     int day5total = 0;
     int day6total = 0;
     int day7total = 0;
     int day1number = 0;
     int day2number = 0;
     int day3number = 0;
     int day4number = 0;
     int day5number = 0;
     int day6number = 0;
     int day7number = 0;
     int i = 1;
     int n;
     int file_count = 1;
     char buffer[50];
     char day[50];
     FILE *fp;
     char filename[50];


while ( i < 10 ) 
{
     
   sprintf(filename,"hw04-data-0%d.csv", i);
   fp=fopen(filename, "r");


   


   while(fgets(buffer, sizeof(buffer), fp))
    {
      sscanf(buffer,"%[^,] ,%d", day, &n);
      /*printf("day is %s, amt is %d\n", day, n);*/


             if(strcmp(day, "Sunday")==0) 
                   {
                    day1total++;
                    day1number+=n;
                    }
 
             if(strcmp(day, "Monday")==0) 
                   {
                    day2total++;
                    day2number+=n;
                   }
             
             if(strcmp(day, "Tuesday")==0) 
                   {
                    day3total++;
                    day3number+=n;
                   } 


             if(strcmp(day, "Wednesday")==0) 
                   {
                    day4total++;   
                    day4number+=n;
                   } 
             if(strcmp(day, "Thursday")==0) 
                   {
                    day5total++;
                    day5number+=n;
                   }




             if(strcmp(day, "Friday")==0) 
                   {
                    day6total++;
                    day6number+=n;
                   }             
                   
             if(strcmp(day, "Saturday")==0) 
                   {
                    day7total++;
                    day7number+=n;
                   } 




}
printf("File %2d:  Sun, %d, %d; Mon, %d, %d; Tue, %d, %d; Wed,"
       "%d, %d; Thu, %d, %d; Fri, %d, %d; Sat, %d, %d\n",     file_count, day1total, day1number, day2total, day2number, day3total, day3number, day4total, 
                                                               day4number, day5total, day5number, day6total, day6number, day7total, day7number);
file_count++;             


      day1total = 0;
      day2total = 0;
      day3total = 0;
      day4total = 0;
      day5total = 0;
      day6total = 0;
      day7total = 0;
      day1number = 0;
      day2number = 0;
      day3number = 0;
      day4number = 0;
      day5number = 0;
      day6number = 0;
      day7number = 0;
i++;


}






i=10;


while ( i < 100 ) 
{
     
   sprintf(filename,"hw04-data-%d.csv", i);
   if((fp=fopen(filename, "r")) == NULL) 
   {
      printf("Error: file failed to open!\n");
      getchar();
      return 1;
   }


   


   while(fgets(buffer, sizeof(buffer), fp))
    {
      sscanf(buffer,"%[^,], %d",day, &n);
    


             if(strcmp(day, "Sunday")==0) 
                   {
                    day1total++;
                    day1number+=n;
                    }
 
             if(strcmp(day, "Monday")==0) 
                   {
                    day2total++;
                    day2number+=n;
                   }
             
             if(strcmp(day, "Tuesday")==0) 
                   {
                    day3total++;
                    day3number+=n;
                   } 


             if(strcmp(day, "Wednesday")==0) 
                   {
                    day4total++;   
                    day4number+=n;
                   } 
             if(strcmp(day, "Thursday")==0) 
                   {
                    day5total++;
                    day5number+=n;
                   }




             if(strcmp(day, "Friday")==0) 
                   {
                    day6total++;
                    day6number+=n;
                   }             
                   
             if(strcmp(day, "Saturday")==0) 
                   {
                    day7total++;
                    day7number+=n;
                   }              


}


printf("File %2d:  Sun, %d, %d; Mon, %d, %d; Tue, %d, %d; Wed,"
       "%d, %d; Thu, %d, %d; Fri, %d, %d; Sat, %d, %d\n",     file_count, day1total, day1number, day2total, day2number, day3total, day3number, day4total, 
                                                               day4number, day5total, day5number, day6total, day6number, day7total, day7number);
file_count++;             


      day1total = 0;
      day2total = 0;
      day3total = 0;
      day4total = 0;
      day5total = 0;
      day6total = 0;
      day7total = 0;
      day1number = 0;
      day2number = 0;
      day3number = 0;
      day4number = 0;
      day5number = 0;
      day6number = 0;
      day7number = 0;
i++;
}


getchar();
return 0;
}

1. You need to check for fopen failure on line 34.
2. You need to close your file when you're done with it (after your while (fgets...) loop).
3. You can combine the loops. To get the right file name, use d in your sprintf(filename, ...), which will make sure the number is two digits and zero-padded.

Sorry if this is a stupid question but what do you mean on number 3 add a d to make sure it's double padded?

And also how do I check the file opening failure?

I put fclose(fp); in there.
Glad you noticed that, I need to make a habit of putting it in before I even start to write the code.

anduril meant to say %02d (that's a zero before the two). So like this:

Code:

sprintf(filename,"hw04-data-%02d.csv", i);

Just remember that whenever you find yourself copying/pasting big sections of code, there's probably a better way to do it.

Also, whenever you find yourself using a bunch of variables that only differ by a number, you probably should be using arrays.

Code:

int total[7];
int number[7];

// Access them with indices 0 to 6. So, for Sunday:
total[0]++;
number[0] += n;

// Zero them in a loop:
for (j = 0; j < 7; j++)
    total[j] = number[j] = 0;

Yea, that's my bad lol. I saw that right after I posted this and felt really foolish

But I changed it to where it just uses

Code:

   sprintf(filename,"hw04-data-%02d.csv", i);

as you said. and increment i every file.

Could you please advise me in how to check that they are opening correctly? Or would that even be the problem? First file prints everything perfectly then goes to a new line and prints segmentation fault.

You're supposed to check that fp is non-null after fopen. Something like this:

Code:

fp=fopen(filename, "r");
if (!fp) {
    fprintf(stderr, "Couldn't open file: %s\n", filename);
    continue;  // go to top of outer loop
}

BTW, count and total only have to be size 7. And file_count is really the same thing as i.

Yea I changed the i out for file_count because I noticed that too.

I tried your

Code:

fp=fopen(filename, "r");
if (!fp) {
    fprintf(stderr, "Couldn't open file: %s\n", filename);    continue;  // go to top of outer loop
}

But continue seemed to create an infinite loop. It just kept printing the Couldn't open file over and over.

So I changed continue with exit(1)
and it printed the Couldn't open file once.

But either way that means it's still not opening the 2nd file I believe. Or something along those lines?


I also tried this because it's the way our teacher taught us how to check for NULL and it's printing the same thing...

Code:

if ( (fp = fopen(filename, "r" )) == NULL )
    {
    printf("Couldn't open file\n");
    exit(1); 
    }

Here is my revised code as of now. So the only problem should be opening the next file, or maybe I'm closing the first file incorrectly.

Code:

int main(void)
 {
     /* Declares all variables needed */         
     int count[7]= {0}; 
     int total[7]={0};
     int j = 0;
     int n;
     int file_count = 1;
     char buffer[50];
     char day[50];
     FILE *fp;
     char filename[50];


     /* While loop that goes through each file */
while ( file_count < 100 ) 
{
     /* Takes each filename and stores in array "filename" */  
   sprintf(filename,"hw04-data-%02d.csv", file_count);


     /* Opens the file */
   if ( (fp = fopen(filename, "r" )) == NULL )
    {
    printf("Couldn't open file\n");
    exit(1); 
    }


     /* While loop that gets the file and stores the string in "day" and the number in "n" */
   while(fgets(buffer, sizeof(buffer), fp))
    {
      sscanf(buffer,"%[^,] ,%d", day, &n);


     /* Seven if loops adding the number of times a day was seen, storing it in the count spot for that day */
     /* and getting the number after the week and adding it to the total spot for that day */ 
             if(strcmp(day, "Sunday")==0) 
                   {
    count[0]++;
    total[0] += n;
                    }
 
             if(strcmp(day, "Monday")==0) 
                   {
    count[1]++;
    total[1] += n;
                   }
             
             if(strcmp(day, "Tuesday")==0) 
                   {
    count[2]++;
    total[2] += n;
                   } 

             if(strcmp(day, "Wednesday")==0) 
                   {
    count[3]++;
    total[3] += n;
                   } 
             if(strcmp(day, "Thursday")==0) 
                   {
    count[4]++;
    total[4] += n;
                   }

             if(strcmp(day, "Friday")==0) 
                   {
    count[5]++;
    total[5] += n;
                   }             
                   
             if(strcmp(day, "Saturday")==0) 
                   {
    count[6]++;
    total[6] += n;
                   } 
    }


printf("File %2d:  Sun, %d, %d; Mon, %d, %d; Tue, %d, %d; Wed,"
       "%d, %d; Thu, %d, %d; Fri, %d, %d; Sat, %d, %d\n",     file_count,  count[0], total[0], count[1], total[1], count[2], total[2], 
                                                                           count[3], total[3], count[4], total[4], count[5], total[5], count[6], total[6]);
/* Close the open file */                                                                          
fclose(fp);                                                                           
  
/* Adds 1 to the loop and shows which file we are on */             
file_count++;


/* Zero them in a loop */
for (j = 0; j < 7; j++)
    total[j] = count[j] = 0;
}
getchar();
return 0;
}

You're right about the infinite loop. I should've incremented file_count before the continue to go on and try the next file. But exit is good too.

You need to check the actual filenames to see if your generated names match. Do a dir (or ls) of the directory and see what the names look like and that all the files are actually there.

BTW, your indentation is getting a little sketchy.

haha ok I'll fix the indentation. Sorry about that.
It seems all the file names are hw-04-data-01.csv
hw-04-data-01.csv
etc.

Weird, I guess I'll just have to mess around with it a little more and do a little more research. Thanks for all the help so far!

The two filenames you gave are identical. That can't be right, unless they're in different directories.

Sorry I meant to write hw-04-data-02.csv
Typo on my part.

Anyways I found the problem.
For some reason I didn't have

hw-04-data-02.csv in my folder. I probably messed with it when I was moving folders or something. Anyways I moved that one back and the program works perfect.

easy fix. But I guess it's better to have these stupid problems then really difficult ones =P

Thanks for all your help oogabooga.