var calculatedDeliveryDate = new DateTime(2022, 5, 10);

var desiredDeliveryDate = new DateTime(2012, 5, 20);

// This is "old-style". Passing DateTime values around means copying memory.

DateTime GetDeliveryDateByValue(DateTime calc, DateTime desired)

{

if (calc < desired)

{

return desired;

}

else

{

return calc;

}

}

Console.WriteLine(GetDeliveryDateByValue(

calculatedDeliveryDate,

desiredDeliveryDate));

// This is "new-style". Passing and returning DateTime values by reference does not need to copy memory.

ref DateTime GetDeliveryDateByRef(ref DateTime calc, ref DateTime desired)

{

if (calc < desired)

{

return ref desired;

}

else

{

return ref calc;

}

}

Console.WriteLine(GetDeliveryDateByRef(

ref calculatedDeliveryDate,

ref desiredDeliveryDate));

// Example for writing to the returned reference

var tictactoeBoard = string.Empty.PadLeft(9, '_').ToCharArray();

ref char GetElement(int x, int y) => ref tictactoeBoard[y * 3 + x];

GetElement(1, 1) = 'X';

Console.WriteLine(tictactoeBoard);