Use C# regex to convert casing in a string

Question

how can I convert this string:

bKk_035A_paint-House_V003
to
BKK_035a_paint-House_v003

with a regular expression (e.g. Regex.R

Answer 1

the Regex doesn't match the first string...

I assume you want the first 3 chars upper case, and the rest lowercase?

here's a first pass:

const string mod = @"^([a-z][a-z0-9]{1,2})(_\d{3}[a-z]{0,2}_[a-z]+_v{1}\d{3,5})$";
var converted = 
    new Regex(mod, RegexOptions.IgnoreCase)
        .Replace(input1, 
            m => string.Format(
                   "{0}_{1}",
                   m.Groups[1].ToString().ToUpper(),
                   m.Groups[2].ToString().ToLower()
                 )
                );