System.Numerics.BigNumber.FormatBigInteger C# (CSharp) Méthode

        internal static string FormatBigInteger(BigInteger value, string format, NumberFormatInfo info)
        {
            int digits = 0;
            char fmt = ParseFormatSpecifier(format, out digits);
            if (fmt == 'x' || fmt == 'X')
                return FormatBigIntegerToHexString(value, fmt, digits, info);

            bool decimalFmt = (fmt == 'g' || fmt == 'G' || fmt == 'd' || fmt == 'D' || fmt == 'r' || fmt == 'R');

            if (value._bits == null)
            {
                if (fmt == 'g' || fmt == 'G' || fmt == 'r' || fmt == 'R')
                {
                    if (digits > 0)
                        format = string.Format(CultureInfo.InvariantCulture, "D{0}", digits.ToString(CultureInfo.InvariantCulture));
                    else
                        format = "D";
                }
                return value._sign.ToString(format, info);
            }


            // First convert to base 10^9.
            const uint kuBase = 1000000000; // 10^9
            const int kcchBase = 9;

            int cuSrc = value._bits.Length;
            int cuMax;
            try
            {
                cuMax = checked(cuSrc * 10 / 9 + 2);
            }
            catch (OverflowException e) { throw new FormatException(SR.Format_TooLarge, e); }
            uint[] rguDst = new uint[cuMax];
            int cuDst = 0;

            for (int iuSrc = cuSrc; --iuSrc >= 0;)
            {
                uint uCarry = value._bits[iuSrc];
                for (int iuDst = 0; iuDst < cuDst; iuDst++)
                {
                    Debug.Assert(rguDst[iuDst] < kuBase);
                    ulong uuRes = NumericsHelpers.MakeUlong(rguDst[iuDst], uCarry);
                    rguDst[iuDst] = (uint)(uuRes % kuBase);
                    uCarry = (uint)(uuRes / kuBase);
                }
                if (uCarry != 0)
                {
                    rguDst[cuDst++] = uCarry % kuBase;
                    uCarry /= kuBase;
                    if (uCarry != 0)
                        rguDst[cuDst++] = uCarry;
                }
            }

            int cchMax;
            try
            {
                // Each uint contributes at most 9 digits to the decimal representation.
                cchMax = checked(cuDst * kcchBase);
            }
            catch (OverflowException e) { throw new FormatException(SR.Format_TooLarge, e); }

            if (decimalFmt)
            {
                if (digits > 0 && digits > cchMax)
                    cchMax = digits;
                if (value._sign < 0)
                {
                    try
                    {
                        // Leave an extra slot for a minus sign.
                        cchMax = checked(cchMax + info.NegativeSign.Length);
                    }
                    catch (OverflowException e) { throw new FormatException(SR.Format_TooLarge, e); }
                }
            }

            int rgchBufSize;

            try
            {
                // We'll pass the rgch buffer to native code, which is going to treat it like a string of digits, so it needs
                // to be null terminated.  Let's ensure that we can allocate a buffer of that size.
                rgchBufSize = checked(cchMax + 1);
            }
            catch (OverflowException e) { throw new FormatException(SR.Format_TooLarge, e); }

            char[] rgch = new char[rgchBufSize];

            int ichDst = cchMax;

            for (int iuDst = 0; iuDst < cuDst - 1; iuDst++)
            {
                uint uDig = rguDst[iuDst];
                Debug.Assert(uDig < kuBase);
                for (int cch = kcchBase; --cch >= 0;)
                {
                    rgch[--ichDst] = (char)('0' + uDig % 10);
                    uDig /= 10;
                }
            }
            for (uint uDig = rguDst[cuDst - 1]; uDig != 0;)
            {
                rgch[--ichDst] = (char)('0' + uDig % 10);
                uDig /= 10;
            }

            if (!decimalFmt)
            {
                // sign = true for negative and false for 0 and positive values
                bool sign = (value._sign < 0);
                // The cut-off point to switch (G)eneral from (F)ixed-point to (E)xponential form
                int precision = 29;
                int scale = cchMax - ichDst;

                return FormatProvider.FormatBigInteger(precision, scale, sign, format, info, rgch, ichDst);
            }

            // Format Round-trip decimal
            // This format is supported for integral types only. The number is converted to a string of
            // decimal digits (0-9), prefixed by a minus sign if the number is negative. The precision
            // specifier indicates the minimum number of digits desired in the resulting string. If required,
            // the number is padded with zeros to its left to produce the number of digits given by the
            // precision specifier.
            int numDigitsPrinted = cchMax - ichDst;
            while (digits > 0 && digits > numDigitsPrinted)
            {
                // pad leading zeros
                rgch[--ichDst] = '0';
                digits--;
            }
            if (value._sign < 0)
            {
                string negativeSign = info.NegativeSign;
                for (int i = info.NegativeSign.Length - 1; i > -1; i--)
                    rgch[--ichDst] = info.NegativeSign[i];
            }
            return new string(rgch, ichDst, cchMax - ichDst);
        }
    }