In what cases is a comparison of reference data types performed?

In C#, comparison of reference types is performed in the following cases:

• ReferenceEquals comparison — checks whether two variables refer to the same object in memory.

• Overriding Equals() — for comparing the contents of objects rather than their addresses.

• Operators == and != — by default, compare references for reference types, but can be overloaded to compare contents.

Example:

class Person {
    public string Name;
    public override bool Equals(object obj) {
        if (obj is Person other) {
            return this.Name == other.Name;
        }
        return false;
    }
    public override int GetHashCode() => Name.GetHashCode();
}

var p1 = new Person { Name = "Alice" };
var p2 = new Person { Name = "Alice" };

bool areSameReference = Object.ReferenceEquals(p1, p2); // false
bool areEqual = p1.Equals(p2); // true

Thus, comparison of reference types is either for checking if variables refer to the same object or for comparing the contents of objects if the Equals method is overridden.