Rounding a decimal number to fixed number and fixed length

First of all, sorry. I am not a c# programer, but I had the same problem time ago and I found no built-in function. So I programmed my own function to do that. Here is what I did.

CString CMyDoc::RoundToNDecimals (double dValue, const int nDec)
{	double dTemp = 0, dFract = 0, dInt = 0, dRes = 0;
	// Operations to round up the nth decimal number if necessary
	dTemp = dValue*pow(10,nDec);
	dFract = modf (dTemp, &dInt);
	if (dFract >= 0.5)
		dInt++;
	dRes = dInt/pow(10,nDec);
        // Giving a variable string according to number and desired decimals as result
	CString szResult;
	szResult.Format ("%s%f", szResult, dRes);
	int nLarge = szResult.GetLength ();
	for (int i = 0; i < nLarge; i++)
	{	nCount++;
		CString cLetter = szResult.GetAt (i);
		if (cLetter == ".")
		{	nCount += nDec;
			break;
		}
	}
	// Truncate the string to be placed in the screen
	LPTSTR pStr = szResult.GetBufferSetLength (nCount);
	szResult.ReleaseBuffer ();

	return szResult;
;
}

I hope it helps you

Edit: I think there is no way to put 44.600 in number format, zeros at the right in decimal numbers are not considered.

Edit_2: Best answer in required language above... forget this one

I prefer this way:

double val = 44.599521;
string formattedValue = String.Format("{0:#.000}", val);