what is the difference between visitor and strategy pattern?

Question

I have learned both the patterns but did not understand the differences between these two patterns.

I do not know scenarios, when and where to use these patterns.

Can any one explain the differences and use cases?

Answer 1

The main difference is that the Strategy Pattern encapsulates a single group of related behaviors, while the Visitor Pattern encapsulates multiple such groups.

• You should use the Strategy Pattern when you need to encapsulate a behavior - If you have a family of algorithms and you need to choose among them at run time, you should use Strategy Pattern. This is very common: it happens every time you program to an interface.
• You should use the Visitor Pattern to implement double dispatch - If you have a group of algorithms that need to be virtual in relation to more than one object. This is far less common, in part because it is much harder to implement.