How do I check if an object is equal to a new object of the same class?

Question

If I have a object like: ``` public class Person { public int id {get;set;} public string name {get;set;} } ``` And I want the behavior: ``` Person a = new Person(); Person b = new Person(); a == b; ``` and that a == b returns true, do I have to override the Object.Equals() method? or is there some other way of doing it without overriding the Equals method? EDIT I want to compare data, as I want to know if a external method that I call returns a new object or a object with different data than a new object

Accepted Answer

There are a couple of ways you can do this. By default `Equals()` and `==` check for reference equality, meaning:

```
Person a = new Person();
Person b = a:

a.Equals(b); //true
a == b; //true
```

And therefore, the objects are not compared for value equality, meaning:

```
Person a = new Person { id = 1, name = "person1" };
Person b = new Person { id = 1, name = "person1" };

a.Equals(b); //false
a == b; //false
```

To compare objects for their values you can override the `Equals()` and `GetHashcode()` methods, like this:

```
public override bool Equals(System.Object obj)
{
    if (obj == null)
        return false;

Person p = obj as Person;
    if ((System.Object)p == null)
        return false;

return (id == p.id) && (name == p.name);
}

public bool Equals(Person p)
{
    if ((object)p == null)
        return false;

return (id == p.id) && (name == p.name);
}

public override int GetHashCode()
{
    return id.GetHashCode() ^ name.GetHashCode();
}
```

Now you will see other results when comparing:

```
Person a = new Person { id = 1, name = "person1" };
Person b = new Person { id = 1, name = "person1" };
Person c = a;

a == b; //false
a == c; //true
a.Equals(b); //true
a.Equals(c); //true
```

The `==` operator is not overridden and therefore still does reference comparison. This can be solved by overloading it as well as the `!=` operator:

```
public static bool operator ==(Person a, Person b)
{
    if (System.Object.ReferenceEquals(a, b))
        return true;

if ((object)a == null || (object)b == null)
        return false;

return a.id == b.id && a.name == b.name;
}

public static bool operator !=(Person a, Person b)
{
    return !(a == b);
}
```

Now running the checks results in following:

```
Person a = new Person { id = 1, name = "person1" };
Person b = new Person { id = 1, name = "person1" };
Person c = a;

a == b; //true
a == c; //true
a.Equals(b); //true
a.Equals(c); //true
```

How do I check if an object is equal to a new object of the same class?

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