Factorial Function (MFC - String version)

gistfile1.cpp

#define CUT_LENGTH ??

CString Fact(int end){
	CString num1 = _T("1");
	CString num2 = _T("");
	CString num3 = _T("");

	for(int i = 1; i <= end; ++i){
		unsigned int tmp = 0;
		num2 = _T("");
		num3 = _T("");

		while(num1.GetLength() > CUT_LENGTH){
			num2 = num1.Right(CUT_LENGTH);
			num1 = num1.Left(num1.GetLength() - CUT_LENGTH);
			unsigned int x = _tstoi(num2) * i;
			num2.Format("%u", x + tmp);
			tmp = 0;
			if(num2.GetLength() > CUT_LENGTH){
				tmp = _tstoi(num2.Left(num2.GetLength() - CUT_LENGTH));
				num2 = num2.Right(CUT_LENGTH);
			}
			else if(num2.GetLength() < CUT_LENGTH){
				while(num2.GetLength() < CUT_LENGTH){
					num2 = _T("0") + num2;
				}
			}
			num3.SetString(num2 + num3);
		}
		unsigned int y = _tstoi(num1) * i;
		num1.Format("%u", y + tmp);
		tmp = 0;
		num1 = num1 + num3;
	}

	return num1;
}