System.Numerics.BigNumber.ParseFormatSpecifier C# (CSharp) Метод

        internal static char ParseFormatSpecifier(string format, out int digits)
        {
            digits = -1;
            if (string.IsNullOrEmpty(format))
            {
                return 'R';
            }

            int i = 0;
            char ch = format[i];
            if (ch >= 'A' && ch <= 'Z' || ch >= 'a' && ch <= 'z')
            {
                i++;
                int n = -1;

                if (i < format.Length && format[i] >= '0' && format[i] <= '9')
                {
                    n = format[i++] - '0';
                    while (i < format.Length && format[i] >= '0' && format[i] <= '9')
                    {
                        n = n * 10 + (format[i++] - '0');
                        if (n >= 10)
                            break;
                    }
                }
                if (i >= format.Length || format[i] == '\0')
                {
                    digits = n;
                    return ch;
                }
            }
            return (char)0; // Custom format
        }