Strange things (double increment needed????)

Hi guys, I've got a really strange problem with my program that I have written for an assignment that is due today. Below is a sample program that I have written that demonstrates the weird thing that keeps happening to me:*/

Code:

---

#include <stdio.h>

int main()
{
        char fileName[30];
        char location[100][30];
        double depth[100];
        FILE *filePtr;
        int i, j;
       
        printf("Enter name of file to load: ");
        fgets(fileName, sizeof(fileName),stdin);
        strtok(fileName, "\n");
        printf("\n");
        filePtr = fopen(fileName, "r");
        if(filePtr == NULL)
                return 0;
        else
        {
               
               
                for(i = 0; i < 100; i++)
                {       
                        if(feof(filePtr))
                        {
                                break;
                        }
                                       
                fgets (location[i],sizeof(location[i]),filePtr);
                strtok(location[i], "\n");           
                fscanf(filePtr,"%lf", &depth[i]);
                }
        }
        fclose(filePtr);       
        for(j=0; j<i;j = j+2)
        {
                printf("%s\n%lf\n", location[j], depth[j]);
        }

        return 0;
}

---

/*The Program runs perfectly how it should 'like this', What I cant understand is why I need to increment j by 2?
because for some reason the for loop that reads the data from a file only assignes the correct values of depth and location to every second array element??? Am I missing something, I am really stumpped by this would appreciate the help.

btw an example of a file is
Name:
eldorado.txt
Contents of file:
Eldorado 01
22.32
Eldorado 02
67.93


ARRRRRRRGGGGGGGG it doesnt make sense!!!!!!!!!!!!!!! :(

My guess would be that you aren't getting the right data from your fscanf(). Try checking the return value from fscanf(), e.g.

Code:

---

if (fscanf("%lf", &...) != 1)
{
  printf("Wrong result from fscanf\n");
}

---

--
Mats

Quote:

---

Originally Posted by dezz101

Hi guys, I've got a really strange problem with my program that I have written for an assignment that is due today.

Code:

---

       
                      strtok(location[i], "\n");

---

---

Are you using strtok to chomp the \n in location[i]?

But then fscanf leaves the next newline in filePtr, so on odd iterations of your loop that remaining \n ends up in location[i], is eliminated by strtok (leaving location[i] with nothing) and then the next line is a string, so fscanf leaves it for the next (properly ordered) iteration.

Throw enough printf's into the right place and you'll see what I mean.

ps. if you change fscanf to take this: "%lf\n" you will be fine, since depth[i] will only contain a float anyway.

THANK YOU VERY VERY VERY MUCH!!!!!!!!!! I have to finish off the assignment and then have alook at how this works, but you solved the problem and for that I thank you mate. cheers

Funny how the same problem crops up close together:
http://cboard.cprogramming.com/showthread.php?t=108708

--
Mats