private static string FormatGeneral(NumberStore ns, int precision, NumberFormatInfo nfi, bool upper, bool roundtrip)
{
if (ns.ZeroOnly)
return "0";
precision = precision > 0 ? precision : ns.DefaultPrecision;
int exponent = 0;
bool expMode = (ns.IsDecimalSource && precision == ns.DefaultPrecision ? false : (ns.IntegerDigits > precision || ns.DecimalPointPosition <= -4));
if (expMode)
{
while (!(ns.DecimalPointPosition == 1 && ns.GetChar(0) != '0'))
{
if (ns.DecimalPointPosition > 1)
{
ns.Divide10(1);
exponent++;
}
else
{
ns.Multiply10(1);
exponent--;
}
}
}
precision = precision < ns.DefaultPrecision + 2 ? (precision < ns.DefaultMaxPrecision ? precision : ns.DefaultMaxPrecision) : ns.DefaultPrecision + 2;
StringBuilder cb = new StringBuilder(ns.IntegerDigits + precision + 16);
if (expMode)
{
if (ns.RoundDecimal(precision - 1))
{
ns.Divide10(1);
exponent++;
}
}
else if (!roundtrip)
{
if (ns.IsDecimalSource)
ns.RoundPos(precision);
else
ns.RoundDecimal(precision, true, false);
}
if (!ns.Positive)
{
cb.Append(nfi.NegativeSign);
}
ns.AppendIntegerString(ns.IntegerDigits > 0 ? ns.IntegerDigits : 1, cb);
if (ns.DecimalDigits > 0)
{
cb.Append(nfi.NumberDecimalSeparator);
ns.AppendDecimalString(ns.DecimalDigits, cb);
}
if (expMode)
{
if (upper)
cb.Append('E');
else
cb.Append('e');
if (exponent >= 0)
cb.Append(nfi.PositiveSign);
else
{
cb.Append(nfi.NegativeSign);
exponent = -exponent;
}
if (exponent == 0)
{
cb.Append('0', 2);
}
else if (exponent < 10)
{
cb.Append('0');
cb.Append(digitLowerTable[exponent]);
}
else if (exponent < 100)
{
cb.Append(digitLowerTable[exponent / 10 % 10]);
cb.Append(digitLowerTable[exponent % 10]);
}
else if (exponent < 1000)
{
cb.Append(digitLowerTable[exponent / 100 % 10]);
cb.Append(digitLowerTable[exponent / 10 % 10]);
cb.Append(digitLowerTable[exponent % 10]);
}
}
return cb.ToString();
}