Strange things (double increment needed????)

[dezz101]

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:*/

#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!!!!!!!!!!!!!!!

[matsp]

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

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

--
Mats

[MK27]

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

	
               	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.

[dezz101]

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

[matsp]

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

--
Mats