Classes and Objects

Fields

Fields store object state that methods and other code can read or update.

field A field is a variable stored inside an object.

Fields

start
Fields.cs
Replay: real traced execution (multi-file project)
using System;

class Counter
{
    public int Value;
}

class Program
{
    static void Main()
    {
        int start = 2;
        Counter counter = new Counter();
        counter.Value = start;
        counter.Value = counter.Value + 1;

        Console.WriteLine($"start={start}");
        Console.WriteLine($"value={counter.Value}");
    }
}

using System;

class Counter
{
    public int Value;
}

class Program
{
    static void Main()
    {
        int start = 0;
        Counter counter = new Counter();
        counter.Value = start;
        counter.Value = counter.Value + 1;

        Console.WriteLine($"start={start}");
        Console.WriteLine($"value={counter.Value}");
    }
}

using System;

class Counter
{
    public int Value;
}

class Program
{
    static void Main()
    {
        int start = 5;
        Counter counter = new Counter();
        counter.Value = start;
        counter.Value = counter.Value + 1;

        Console.WriteLine($"start={start}");
        Console.WriteLine($"value={counter.Value}");
    }
}

  1. start ← 2, counter ← Counter, counter.Value ← 2

    9{10    static void Main()11    {12        int start→ 2 = 2; //@start=0, 513        Counter counter→ Counter = new Counter();14        counter.Value→ 2 = start2;15        counter.Value→ 3 = counter.Value + 1;1617        Console.WriteLine($"start={start2}");18        Console.WriteLine($"value={counter.Value3}");19    }
    outputstart=2
value=3

  1. start ← 0, counter ← Counter, counter.Value ← 0

    9{10    static void Main()11    {12        int start→ 0 = 0;13        Counter counter→ Counter = new Counter();14        counter.Value→ 0 = start0;15        counter.Value→ 1 = counter.Value + 1;1617        Console.WriteLine($"start={start0}");18        Console.WriteLine($"value={counter.Value1}");19    }
    outputstart=0
value=1

  1. start ← 5, counter ← Counter, counter.Value ← 5

    9{10    static void Main()11    {12        int start→ 5 = 5;13        Counter counter→ Counter = new Counter();14        counter.Value→ 5 = start5;15        counter.Value→ 6 = counter.Value + 1;1617        Console.WriteLine($"start={start5}");18        Console.WriteLine($"value={counter.Value6}");19    }
    outputstart=5
value=6