chars

/*
 * call-seq:
 *   strio.each_char {|char| block }  -> strio
 *
 * See IO#each_char.
 */
static VALUE
strio_each_char(self)
    VALUE self;
{
    struct StringIO *sio;
    VALUE str;
    const char *ptr;
    size_t len;

    RETURN_ENUMERATOR(self, 0, 0);

    sio = readable(StringIO(self));
    str = sio->string;
    ptr = RSTRING_PTR(str);
    len = RSTRING_LEN(str);

    while (sio->pos < len) {
        int pos = sio->pos;
        char c = ptr[pos];
        int n = mbclen(c);

        if (len < pos + n) n = len - pos;

        sio->pos += n;
        rb_yield(rb_str_substr(str, pos, n));
    }
    return self;
}