Question: I need to check if the first element of a string is positive integer in C#.
is there a smart Way to do this?
Fx

```
string str = "2001";
if (str.First() == isANumber) {
...                                
}

```

Answer: 
I believe if no sign then it is positive? So just check whether the first sybmol is not `"-"`. 

EDIT: As Mark noted in a comment below - it may depend on a culture which is used.
```
if(Char.IsDigit(str.First()))
{
}

```