Question

I used it in C#

var validString = new Regex(@"^[a-z][a-z\d!@#$%\^&*()\-+]{0,7}$(?<=\d\D+)", RegexOptions.Compiled); 

I am trying to enforce the following rules for password creation

•Not have upper-case letters. 
•Begin with a letter. 
•Have at least 1 digit(s) not at the beginning and end. 
•Have up to 8 alphanumeric 
•Does NOT have any symbols like @#$ characters (symbols like !@#$%^&*()-+). 

Any help would be appreciated

Answer 1

Almost identical, except for:

• new RegExp instead of new Regex
• No @ before the string
• You can’t use constants for options, only a string with option letters
• You can’t use lookbehinds.

Alternatively use a regex literal:

var validString = /^[a-z](?=[a-z]*[0-9])[a-z0-9]{0,6}[a-z]$/;

Note I changed your regex, since you basically say you can’t have digits at the start or end. I used a lookahead instead to ensure there was a number in there.