What is the relationship between delegates and events?

Question

Delegate does the same job of function pointers. It can be viewed as the function pointers of the managed world. It simply represents the address of a function to call, along with a specific object whose method is to be called.

Many times I read the term Delegate along with the termEvent but I can not see the relationship between them. Is the Event a specific type of delegates?

Answer 1

Short answer: see my article on the topic. Longer answer:

Events are a pattern on top of delegates. They're an implementation of the publisher/subscriber pattern (aka observer pattern), using delegates as the means of representing a subscription.

Whenever you see something like:

public event EventHandler Foo;

you should instead think of two methods:

public void AddFooHandler(EventHandler handler) { ... }
public void RemoveFooHandler(EventHandler handler) { ... }

All that a client from the outside can do is subscribe and unsubscribe. In particular, the client cannot raise the event themselves (without a separate method being provided for that purpose) nor can they "replace" or remove other subscriptions.