Suppose I have a string `foo` and I want to search for the second period, if any.

I'm using this code:

```
 std::size_t start = foo.find_first_of('.');
 if (start != std::string::npos){
     std::size_t next = foo.find_first_of('.', start + 1);
     /*and so on*/

```

I'm wondering if this is well-defined if the first period is at the end of the string.

I think it is since `start + 1` will be on the null-terminator, so I'm not in any danger of accessing any memory I shouldn't.

Am I correct?