DateTime.AddDays() not working as expected

Question

I have this simple program:

        DateTime aux = new DateTime(2012, 6, 12, 12, 24, 0);
        DateTime aux2 = new DateTime(2012, 6, 12, 13, 24, 0);
               


        

Answer 1

It does work but you don't do anything with the return value, try

aux2 = aux2.AddDays(1);

DateTimes share this facet of immutability with Strings.

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EDIT

There is a little paragraph about it on MSDN

This method does not change the value of this DateTime. Instead, it returns a new DateTime whose value is the result of this operation.

Answer 2

You are working with immutable functions.

The DateTime function is immutable, once you set variable equal to it, it cannot change, you can though set new variables equal to a working of the function. The AddDay function takes the variable you put into it, but it does not change the original variable, that remains immutable. So you need to set a new variable equall to the original variable + a day.

So all you really need to do is change

aux2.AddDays(1);

to

aux2 = aux2.Affffdays(1);

and then the rest of your comparison functions should work

Answer 3

DateTime.AddDays returns new DateTime that adds specified number of days. You need to assign it to your variable:

aux2 = aux2.AddDays(1);