<p>Using only ANSI C, what is the best way to, with fair certainty, determine if a C style string is either a integer or a real number (i.e float/double)?</p>

I suppose you could step through the string and check if there are any
```
.
```
characters in it.  That's just the first thing that popped into my head though, so I'm sure there are other (better) ways to be more certain.