Câu hỏi phỏng vấn Rust
Câu hỏi

What is the difference between Copy and Clone in Rust?

Câu trả lời

In Rust, the Copy and Clone traits are both used to create duplicates of values, but they serve different purposes and have distinct characteristics.

Copy Trait

  • Implicit and Inexpensive: The Copy trait allows for implicit copying of values. This means that when a value is assigned to another variable or passed to a function, a bitwise copy is made automatically without the need for an explicit method call. This operation is generally inexpensive as it involves a simple memory copy (memcpy)[1][2][4].
  • Simple Types: The Copy trait is typically used for simple, fixed-size types that can be safely duplicated with a bitwise copy. Examples include primitive types like integers (i32, u32), floating-point numbers (f32, f64), and simple structs that do not manage resources like heap memory[3][5].
  • No Custom Implementation: The behavior of Copy cannot be customized. It is always a shallow, bitwise copy, and the trait cannot be manually implemented by the user; it can only be derived[8].
  • No Drop Implementation: Types that implement Copy cannot also implement the Drop trait, which is used for custom cleanup logic when a value goes out of scope[6].

Clone Trait

  • Explicit and Potentially Expensive: The Clone trait requires an explicit method call (clone()) to create a duplicate of a value. This operation can be more complex and potentially expensive, as it may involve deep copying of data, such as duplicating heap-allocated memory[1][2][4].
  • Customizable: The Clone trait allows for custom implementations, enabling developers to define how a value should be duplicated. This is particularly useful for types that manage resources like heap memory, where a simple bitwise copy would be insufficient or unsafe[5][6].
  • Deep Copy: While Clone can perform deep copies, it is not limited to this. The implementation of Clone can perform an...
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