What does 'y' in the output stand for in C?

Question

I have a problem, I construct a string in a loop and the output of that string to stout displays the string and a character 'y' with two dots above it as the last character.

What is that?

I create the string in this function:

char get_string(char *buf, int ble, FILE *fp, char del)
{
    int i = 0;
    int c;
    char    result;

    memset(buf, 0, BUFLEN);

    do {

        c = fgetc(fp);

        if (c == del) {
            buf[i] = '\0';
            result = c;
            break;
        } else if(c == '\n') {
            buf[i] = '\0';
            result = '\n';
            break;
        } else {
            buf[i] = c;
            i++;
        }

    } while (c != EOF);

    return result;
}

and then use the buf and result as follows in another function:

char    pair[BUFLEN];
char    end;

do {

        end = get_string(pair, BUFLEN, fp, ';');
        printf("Result: %s\n",pair);

} while (pair != NULL);

The last iteration of the above Prints out "Result: y" I have no idea why.

Answer 1

You're using a do-while loop, which means that you're executing the loop body before testing for EOF, so you end up putting EOF in your buffer as well. The EOF value of -1 gets translated into the character range where it corresponds to ÿ. I'd recommend you to just switch to a more usual while loop because it handles this condition more naturally.

Answer 2

ÿ is the glyph for the character which (in Unicode and many ISO-8859-? encodings) has the ordinal value 0xFF. That value, also known in decimal as 255, is also used in some contexts as "the end-of-file character" (aka EOF) -- although there's no standard that defines the character as such (AFAIK), the value -1 is what does get returned in many languages (such as C) when you try to read more from a file that's exhausted ("at end of file").

In practice, therefore, an unexpected ÿ in your output often means that you are erroneously interpreting a byte that's intended to signify "end of something" (a byte encoded with all bits set to one) as if it was part of the text to display.