Thread: Counting Lines

Hi,

Code:

void check_activity(char * this_months, char * last_months)
{
FILE * fp1;
FILE * fp2;
int diff = 0;
int result = 0;
int countA = 0, countB = 0;

#ifdef DEBUG
    printf("In check_activity().\n");
    fflush(NULL);
#endif

   if(!(fp1 = fopen(this_months, "r")))
      error_func("In check_activity().", "Error : fopen(INPUT_FILE)", SYS | FATAL);

   if(!(fp2 = fopen(last_months, "r")))
      error_func("In check_activity().", "Error : fopen(OUTPUT_FILE)", SYS | FATAL);
/*
   while(fscanf(fp1, "%d", &countA) != NULL)
      ;
   while(fscanf(fp2, "%d", &countB) != NULL)
      ;
*/
   if(fp1 != NULL)
   {
      /* Read the number of records */
      fread(&countA, sizeof(int), 1, fp1);
      fclose(fp1);
   }

   if(fp2 != NULL)
   {
      /* Read the number of records */
      fread(&countB, sizeof(int), 1, fp2);
      fclose(fp2);
   }

   diff = countA - countB;

   fclose(fp1);
   fclose(fp2);

printf("this month, last month, difference %d %d %d\n", countA, countB, diff);
#ifdef DEBUG
    printf("Out check_activity().\n");
    fflush(NULL);
#endif
}

I was hoping to establish the difference in the number of lines between two files, but as I have deliberately created two files which have 6 lines and 4 lines respectively, I was expecting an answer of 2

As _you_ will be able to see, that is not happening, perhaps you could tell me why please ?



tia,

I don't think fread is going to help you here (though I may be wrong!!). I would have done it like this...

Code:

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

int main()
{
FILE * fp1;
FILE * fp2;
int diff = 0;
int result = 0;
int countA = 0, countB = 0;
char *this_months = "this_months";
char *last_months = "last_months";
char c;

   if(!(fp1 = fopen(this_months, "r")))
   {
     printf( "\nUnable to open fp1\n" );
     return 0;
   }

   if(!(fp2 = fopen(last_months, "r")))
   {
     printf( "\nUnable to open fp2\n" );
     return 0;
   }

   if(fp1 != NULL)
   {
      /* Read the number of records */
      while(( c = fgetc( fp1 )) != EOF )
        if( c == '\n' )
          countA++;

      fclose(fp1);
   }

   if(fp2 != NULL)
   {
      /* Read the number of records */
      while(( c = fgetc( fp2 )) != EOF )
        if( c == '\n' )
          countB++;

      fclose(fp2);
   }

   diff = countA - countB;

   fclose(fp1);
   fclose(fp2);

   printf("this month, last month, difference %d %d %d\n",
           countA, countB, diff);
}

Obviously, you'll need to convert it back into your function...

ty Morgan

Dave_Sinkula:
Just Lurking:

[nitpicks]
if(fp1 != NULL)
{
/* ... */
}
There's nothing wrong with safety checks,
but if you return from this function when fp1 is NULL,
fp1 will never be NULL later on in the function. Same goes for fp2.

sorry Dave, a little confused, are you saying that I should not use the if test like this

Code:

   if(!(fp1 = fopen(this_months, "r")))
      error_func("In check_activity().", "Error : fopen(INPUT_FILE)", SYS | FATAL);

   if(!(fp2 = fopen(last_months, "r")))
      error_func("In check_activity().", "Error : fopen(OUTPUT_FILE)", SYS | FATAL);

   while((ch = fgetc(fp1)) != EOF)
      if(ch == '\n')
         countA++;
   fclose(fp1);

   while((ch = fgetc(fp2)) != EOF)
      if(ch == '\n')
         countB++;
   fclose(fp2);

   diff = countA - countB;

I have tried this and the results are the same as with the test, however, I do not know enough of the consequences to be able to look further into it !


tia,

ahh - thank you both