Question

I am trying to use string matching in a winforms application .I would like to match the patterns such as bank will be matched by benk or bamk etc so i cannot use

b.nk because then it will not match bamk , it is to give the user a nearest possible option even if the user types wrongly eg in the spelling correction in most applications (but its not for spelling correction)

some other examples : 
Valid list : possible ,bank, easy,thanks
posible matches possible 
benk matches bank
easi matches easy 
eassy matches easy 
Thaks matches Thanks

Answer 1

You need the edit distance not regular expression. Most commonly, the edit operations allowed for this purpose are

1. insert a character
2. delete a character
3. replace a character with another character.

The edit distance is the number of operations needed to change a string to another string. The string with small distance is most likely what you want. For example benk will has small edit distance with bank.