How to read null-terminated strings from file?

[thorster]

Hi!

I am new to C and need some advice here. I have a solution to this problem but I still think there should be a way to do this more efficiently: I have a file where I have stored null-terminated strings including the '\0' char. I now want to read one string from the file stopping after the next '\0'. The strings in the file are at most 31 chars including the null char. I wrote this function to read one string from the file:

static int freadstr(FILE* fid, register char* str, size_t max_size)
{
    int c, count = 0;
    do {
        c = fgetc(fid);
        if (c == EOF) {
            /* EOF means either an error or end of file but
             * we do not care which. Clear file error flag
             * and return -1 */
            clearerr(fid);
            return -1;
        } else {
            /* Cast c to char */
            *str = (char) c;
            count++;
        }
    } while ((*str++ != '\0') && (count < max_size));
    return count;
}

Then in the calling function I do:

size = freadstr(fid, str, 32);
        if (size == -1) {
            /* End of file or file error */
            fprintf(stderr, "File error\n");
            return -1;
        } else if (size == 32) {
            /* Parse error, string was not null-terminated
             * within 31 bytes */
            fprintf(stderr, "Parse error\n");
            return -1;
        }

Is this not more complicated than it need to be?

Thanks,
Jonas

[death_oclock]

That looks like a good implementation to me, and without the comments its really quite short and sweet.

[Ancient Dragon]

Had you terminated the strings with "\n" instead of "\0" then you could have simply called fgets() to read the strings back into memory.