int8_fast_t meets this description (because the range for this particular loop only spans 10, but you should use the int16_ or int32_ versions as appropriate).  int8_fast_t will likely use native-register-sized integers (probably 32 or 64 bit on many architectures).<p>This is IMO very close to the inference you describe, while still providing some stipulations about what you need.<p>int8_fast_t and its siblings are defined in &lt;stdint.h&gt;, described in this article (though it would be nice if the article mentioned them).