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?