public string StringReverse(string str)
    {
        int len = str.Length;
        char[] arr = new char[len];

        for (int i = 0; i < len; i++)
        {
            arr[i] = str[len - 1 - i];
        }

        return new string(arr);
    }

    public int InStr(string TheString, string ToFind)
    {
        return (int)TheString.IndexOf(ToFind);
    }

    public static string Left(string param, int length)
    {
        //we start at 0 since we want to get the characters starting from the
        //left and with the specified lenght and assign it to a variable
        string result = param.Substring(0, length);
        //return the result of the operation
        return result;
    }
    public static string Right(string param, int length)
    {
        //start at the index based on the lenght of the sting minus
        //the specified lenght and assign it a variable
        string result = param.Substring(param.Length - length, length);
        //return the result of the operation
        return result;
    }

    public static string Mid(string param, int startIndex, int length)
    {
        //start at the specified index in the string ang get N number of
        //characters depending on the lenght and assign it to a variable
        string result = param.Substring(startIndex, length);
        //return the result of the operation
        return result;
    }

    public static string Mid(string param, int startIndex)
    {
        //start at the specified index and return all characters after it
        //and assign it to a variable
        string result = param.Substring(startIndex);
        //return the result of the operation
        return result;
    }

    public static bool IsNumeric(object Expression)
    {
        bool isNum;
        double retNum;
        isNum = Double.TryParse(Convert.ToString(Expression), System.Globalization.NumberStyles.Any, System.Globalization.NumberFormatInfo.InvariantInfo, out retNum);
        return isNum;
    }