What's the Difference Between '=default' and '{}' for Default Constructors and Destructors?-C++-php.cn

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What's the Difference Between '=default' and '{}' for Default Constructors and Destructors?

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Dec 22, 2024 pm 12:00 PM

What's the Difference Between

Distinguishing ""=default"" from "{}" for Default Constructors and Destructors

While "=default" and "{}" can seem interchangeable for virtual destructors, they exhibit significant differences when used for default constructors and non-virtual destructors.

Default Constructors

For default constructors, "=default" explicitly directs the compiler to generate a default constructor. In contrast, "{}" results in a user-provided default constructor, altering the class's triviness. Trivial classes allow for efficient memory operations, but user-provided functions, including an empty "{}" default constructor, remove this classification.

Destructors

In the case of virtual destructors, "=default" and "{}" have minimal differences. However, for non-virtual destructors, "=default" signifies a compiler-generated destructor, while "{}" indicates a user-provided destructor. This distinction remains crucial in determining the class's triviness, as user-provided destructors prevent trivial classification.

Therefore, when choosing between "=default" and "{}", consider whether the class should be considered trivial or not. "=default" maintains triviness by delegating function generation to the compiler, whereas "{}" creates user-provided functions, impacting the class's triviness status.

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