c - feof(in) != EOF doesn't make while loop stop when at the end of file?

int main ()
{
    FILE *in;
    in = fopen("input.txt","r");
    char c = fgetc(in);
    while(feof(in) != EOF)
    {

    printf("%c",c);
    c = fgetc(in); 
    }
}

feof(in) != EOF doesn't stop the while loop from stopping but something like !feof(in) seems to work. Any ideas?

Answer

feof doesn't return EOF on end of file; it returns true, which is not equal to EOF.

fgetc will return EOF when it hits end-of-file. Your code should be written as

int main ()
{
    FILE *in;
    in = fopen("input.txt","r");
    int c = fgetc(in);             // note int not char
    while(c != EOF)                // compare c to EOF
    {
      printf("%c",c);

      c = fgetc(in); 
    }
}

You should not use feof as a loop condition, as it won't return true until after you attempt to read past the end of the file, meaning your loop will execute once too often.