System.Globalization.CultureTableRecord.AnsiToLower C# (CSharp) Method

        internal static string AnsiToLower(string testString)
        {
            StringBuilder sb = new StringBuilder(testString.Length);

            for (int ich = 0; ich < testString.Length; ich++) 
            {
                char ch = testString[ich];
                sb.Append(ch <= 'Z' && ch >= 'A' ? (char)(ch - 'A' + 'a') : ch);
            }

            return(sb.ToString());
        }