时间:2019-03-17 标签:c++c-style零初始化{0}

Question

https://en.cppreference.com/w/cpp/language/zero_initialization显示零初始化发生在以下场景中:

int array[32] = {};

;但从未提及此事:

int array[32] = { 0 };

后者是否也会在 C++ 中对整个数组进行零初始化，还是仅对第一个元素进行零初始化？如果是这样，那么结构体也是如此吗？

Answer 1

ISO/IEC N489 §9.4.1州

• ⁽⁵⁾ For a non-union aggregate, each element that is not an explicitly initialized element is initialized as follows:

  • ^(5.1) If the element has a default member initializer (11.4), the element is initialized from that initializer.

  • ^(5.2) Otherwise, if the element is not a reference, the element is copy-initialized from an empty initializer list (9.4.4).

  • ^(5.3) Otherwise, the program is ill-formed.

§9.4.4州

• ^(3.11) Otherwise, if the initializer list has no elements, the object is value-initialized.

标量的

值初始化导致其零初始化。因此，第二个元素仅显式初始化为 0 array[0]，其余元素将被零初始化。

<小时/>

因此，下面的代码

int array[4] = {13};

用值初始化数组

{13, 0, 0, 0}