What is the main difference between shallow copy and deep copy?

The distinction between shallow copy and deep copy primarily revolves around how they handle the copying of objects, particularly with respect to nested objects. A shallow copy only creates a new object, but does not recursively copy objects that are contained within it. Instead, the shallow copy simply copies references to those nested objects. This means that if the original object contains other objects, the shallow copy will still point to the same nested objects as the original, leading to shared references.

In contrast, a deep copy creates copies of all objects, including those nested within the original object. This results in a completely independent copy of the original object and all of its attributes, including nested objects. Consequently, modifications to the nested objects in either the original or the deep copy will not affect the other, as they exist in separate memory spaces.

This explanation highlights why the option stating that shallow copy does not create copies of nested objects while deep copy does is accurate. It clarifies how deeply nested structures are treated differently in each copying method, showcasing the fundamental principle that differentiates these two concepts in object-oriented programming.