feof - How does C handle EOF?

#include
            


int main()
{
 FILE*
            f=fopen("book2.txt","r");
 char a[200];
 while(!feof(f))

            {
 fscanf(f,"%s",a);
 printf("%s ",a);

            printf("%d\n",ftell(f));
 }

 fclose(f);
 return
            0;
} 

I have
the code above. book2.txt contains "abcdef abcdef" with the cursor move to a
newline(ie:abcdef abcdef\n). I get the results
below.

abcdef 6
abcdef
            13
abcdef
            19

I expect
to get

abcdef 6
abcdef
            13
15

What
am I doing wrong?