What is the difference between copy and reference in programming?

What is the difference between copy and reference in programming?

In programming, a copy creates a new instance of a variable, while a reference points to the original variable's memory location.

Can you give me an example of each?

Sure! In Python, if you do a = [1, 2, 3] and then b = a, b is a reference to a. If you modify b, a changes too. But if you do c = a.copy(), c is a separate copy.

What are the implications of using references?

Using references can lead to unintended side effects if you're not careful, as changes to one variable can affect others that reference it.

How does this differ in languages like Java or C++?

In Java, objects are always passed by reference, while primitives are passed by value. In C++, you can choose to pass by reference or by value explicitly.