size

/*
 * call-seq:
 *   strio.size   -> integer
 *
 * Returns the size of the buffer string.
 */
static VALUE
strio_size(self)
    VALUE self;
{
    VALUE string = StringIO(self)->string;
    if (NIL_P(string)) {
        rb_raise(rb_eIOError, "not opened");
    }
    return ULONG2NUM(RSTRING(string)->len);
}