C Sharp :: Remove Specific Char In String

int index = -1;
string NewStr = null;
char[] lower = {'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'};
char[] upper = {'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'};  
foreach (char c in str)

[Code]....

The code above loops through a string and for each character checks to see if it is a lower case character, then checks to see if it an upper case. It then removes it if it is. Leaving only the numbers.

However, it reuses the same string the entire time, never updating the string so it always finds the same (first) character.