Question: I have a List like this:

```
var l = new List<string> {"bla 1.txt","bla 2.txt","bla 10.txt","bla 3.txt"};

```

If i call l.Sort(), the list gets sorted in the order 1,10,2,3 which makes sense from a pure string point of view, but sucks from a User Perspective.

Since I don't want to/can't force my users to name them 01, 02, 03,... I wonder if there is either a built-in method or simple algorithm to detect and sort numbers properly, so that I have 1,2,3,10? Since the numbers are only 1 or 2 characters long (i.e., no more than 99) I could possibly do a regex that temporarily prefixes all 1-digit numbers with a 0 and sort, but before I reinvent the wheel I wonder if something already exists?

.net 3.5SP1 if that matters, not 4.0

Answer: 
The best approach is making use of `IComparer`. This has already been done and can be [found on code project](http://www.codeproject.com/KB/recipes/csnsort.aspx).
You could implement your own IComparer that maybe uses a regular expression on the input ("bla 1.txt"), converts that to an int, and peforms the comparison on that parsed value.