validating textbox in c#.net,

[chandruswami]

In validating textbox in c#.net,
I want to allow the user to enter value based on the conditions.

Not Allowed
------------
1. Only special characters not allowed (Ex: !@#)
2. Only Numbers not allowed (Ex: 3456)

Allowed
---------
3. characters only small letters allowed. (Ex: asd)
4. characters only capital letters allowed. (Ex: ASD)
5. characters having both capital and small letters allowed. (Ex: AsdF)
6. Value including Alphabets,numbers and special characters allowed (Ex: A23$, a67%)

I want these case to be implemented through RegularExpressions

Can anyone help me with ideas?,........./

[ddanbe]

Perhaps you could have a look at this snippet: http://www.daniweb.com/code/snippet217420.html