O'Reilly Confused me on classes

Herboren

Lets start with a piece from the book:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace TernaryOperator
{
class Time
{
// Public Member Variables
int Year;
int Month;
int Date;
int Hour;
int Minute;
int Second;

    // Public accessor methods
    public void DisplayCurrentTime()
    {
        Console.WriteLine("{0}/{1}/{2} {3}:{4}:{5}",
            Month, Date, Year, Hour,Minute,Second);
        Console.ReadKey();
    }

    // Constructor
    public Time(System.DateTime dt)
    {
        Year = dt.Year;
        Month = dt.Month;
        Date = dt.Day;
        Hour = dt.Hour;
        Minute = dt.Minute;
        Second = dt.Second;
    }
}

class Program
{
    static void Main(string\[\] args)
    {
        System.DateTime currentTime = System.DateTime.Now;
        Time t = new Time(currentTime);
        t.DisplayCurrentTime();
    }

}

}

For the constructor portion, where I declared or created the reference in the constructor, the values aren't actively stored in my variables yet, am I right?

        Year = dt.Year;
        Month = dt.Month;
        Date = dt.Day;
        Hour = dt.Hour;
        Minute = dt.Minute;
        Second = dt.Second;

So that means my 'Time t = new Time(currentTime)' is storing the active vars into my constructor using the 'dt' reference?. Correct? I feel like I am almost lost.

PIEBALDconsult

Herboren wrote:

the values aren't actively stored in my variables yet

Yes, they are, why do you think otherwise? ints are value types.

Lost User

        Time t = new Time(currentTime);

The above code calls the constructor that takes a System.DateTime as input, and copies the values from the DateTime into the new object's variables. So you now have a Time object containing values that correspond to the currentTime object. The next line calls the DisplayCurrentTime() method on the Time object t, which displays the values previously stored. Does that make sense?

The best things in life are not things.

Herboren

Actually that made perfect sense and your put me back on track thank you. And these are all initialized explicitly, correct? And I can implicitly initialize it but changing 'int Second = 30;' as an initializer, not that I would want to but just to get the understanding of implicit and explicit.

Lost User

Herboren wrote:

And these are all initialized explicitly, correct?

Yes, statements of the form:

        Year = dt.Year;

are taking a value from the input parameter (dt) and allocating them to a variable within the current instance of the Time class; i.e. the object currently being constructed by the constructor.

Herboren wrote:

And I can implicitly initialize it but changing 'int Second = 30;' as an initializer, not that I would want to but just to get the understanding of implicit and explicit.

I'm not sure I understand what you mean here: any statement of the form, variable = expression, is an explicit assignment, and can be placed anywhere, either within one of the class methods, or external to it when the access level of a variable allows. For a further discussion of explicit/implicit take a look here[^].

The best things in life are not things.