• C

file processing

i have stock.dat file ( two columns of stocks) and i created the program to read from this file and display two columns of stocks, but i cant figure out how to get the average of each stocks.  actually i have two arrays of stocks with size 20, but when i try to create a function to compute the average i get incorrect answer.   i would be gratitude if you help me with this problem
elinaAsked:
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rbrConnect With a Mentor Commented:
What incorrect answer to you get. What types are stock and total. If they are short integer you got an overrun maybe. Use long or better double.
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rmichelsCommented:
Can you post your source code for your average function?

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scrapdogCommented:
total=0;
for (j=0; j<20; j++) total += stock[j];
avg=stock/20;
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scrapdogCommented:
i mean avg=total/20;

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elinaAuthor Commented:
thanks for all replies.  here is the original code. Average ()doesnt work correctly.
thanks a lot
Elina


#include <stdio.h>
#define SIZE 20

void Average(char [], int);

main()
{
      int i;
      char stock1[SIZE];
      char stock2[SIZE];
      FILE *cfPtr;


      if ((cfPtr = fopen ("STOCK.DAT","r")) == NULL)
            printf("file couldnt be opened\n");

      else {
            printf("%s%\t\t%s\n", "stock 1", "stock 2");
            fscanf(cfPtr, "%s%s", stock1, stock2);

            while (!feof (cfPtr)) {
                  printf("%s\t\t%s\n", stock1, stock2);
                  fscanf(cfPtr, "%s%s", stock1,  stock2);
            }

      }

          Average (stock1, SIZE );
      
            fclose (cfPtr);


            return 0;
}

      void Average(char b[], int size)
{
      int j, temp;
      int  total;
      for (j = 0; j <= size; j++)
      temp += b[j];
      total = temp / 20;
      printf("total %d\t\n", b[j]);

}

      
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scrapdogCommented:
void Average(char b[], int size)
{
int j, temp;
int  total;
for (j = 0; j <= size; j++)
temp += b[j];
total = temp / 20;
printf("total %d\t\n", total)      //this line changed!!!
}

In the printf statement you were printing the last element of the array (in b[j]) instead of the average (in total).
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elinaAuthor Commented:
the average is still incorrect and i cant figure out why.  i got big numbers like 3456789

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scrapdogCommented:
Initialize temp and total to 0.

int temp=0,
int total=0
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scrapdogCommented:
Also change temp=temp/20 to temp=temp/size

This will accomplish the same thing, but will allow the average function to accept arrays other than a size of 20.
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scrapdogCommented:
If rbr's answer didn't work why did you accept it?
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ozoCommented:
What are you reading into stock1?
It looks like it's the characters from your last read of cfPtr
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elinaAuthor Commented:
thanks guys but it still doesnt work.  
for ozo:  i am reading from stock1 and trying to get average
for scrapdog: about answer. i didnt pay attention that i checked it.  i am new here.  
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scrapdogCommented:
Please repost your revised source code.


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elinaAuthor Commented:
#include <stdio.h>
#define SIZE 20

void Average(float []);

main()
{
      int i;
      float stock1[SIZE];      
      float stock2[SIZE];
      FILE *cfPtr;

      if ((cfPtr = fopen ("stock.dat","r")) == NULL)
            printf("file couldnt be opened\n");

      else {
            printf("%s\t%s\n", "stock 1", "stock2");        
            fscanf(cfPtr, "%s\t%s", stock1, stock2);
                                                   
            while (!feof (cfPtr)) {
                  
                  printf("%s\t%s\n", stock1, stock2);            
                  fscanf(cfPtr, "%s\t%s", stock1,stock2);
            }
      }
          Average (stock1);      
            fclose (cfPtr);

            return 0;
}
      void Average(float b[])
{
      int j;
      float  temp, total = 0;
      for (j = 0; j <= SIZE; j++)
      temp = b[j] + total;
      total = temp / SIZE;  // i get '0' here
      printf("total %d\t\n", total);

}

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ozoCommented:
That's a little better, but you're still only reading into stock1[0] and stock2[0], whereas you try to average from 21 elements
(even though they are only declared to contain 20 elements)

also, you're telling fscanf that stock1 and stock2 are character pointers, when they are actualy arrays of float


     for( i=0; i<SIZE; i++ ){ stock1[i]=0; stock2[j]=0; }
     if ((cfPtr = fopen ("stock.dat","r")) == NULL)
     printf("file couldnt be opened\n");

     else {
       i = 0;
     while ( i < SIZE && !feof (cfPtr)) {
     fscanf(cfPtr, "%f\t%f", &stock1[i],&stock2[i]);
     printf("%f\t%f\n", stock1[i], stock2[i]);
     i++;
     }
     }
          Average (stock1);
     fclose (cfPtr);

     return 0;
     }
     void Average(float b[])
     {
     int j;
     float  temp, total = 0;
     for (j = 0; j < SIZE; j++)
     total = b[j] + total;
     total = total / SIZE;  /*// i get '0' here */
     printf("total %f\t\n", total);



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elinaAuthor Commented:
after small changes it works perfectly
thanks a lot  
elina

#include <stdio.h>
#define SIZE 20

void Average(float []);

main()
{
      int i;
      float stock1[SIZE];      
      float stock2[SIZE];
      FILE *cfPtr;

     if ((cfPtr = fopen ("stock.dat","r")) == NULL)
     printf("file couldnt be opened\n");

     else {
          printf("%s\t%s\n", "stock 1", "stock2");        
            fscanf(cfPtr, "%f\t%f", stock1, stock2);
        i = 0;
     while ( i < SIZE && !feof (cfPtr)) {
            fscanf(cfPtr, "%f\t%f", &stock1[i],&stock2[i]);
            printf("%.2f\t%.2f\n", stock1[i], stock2[i]);
            i++;
            }
     }
     Average (stock1);
     fclose (cfPtr);

     return 0;
     }
     void Average(float b[])
     {
     int j;
     float total = 0;
        for (j = 0; j < SIZE; j++)
            total += b[j];
            total = total / SIZE;
            printf("total %.2f\t\n", total);
       }



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