C++11类成员初始化

Question

刚从 C++03 切换到 C++11，我想知道，下面是否定义为始终零初始化所有元素的数组 data？

template<size_t COUNT>
class Test {
public:
    uint32 data[COUNT] = {};
};

Answer 1

是的，这是有保证的； list initialization转aggregate initialization对于数组类型:

Otherwise, if T is an aggregate type, aggregate initialization is performed.

然后进行聚合初始化:

If the number of initializer clauses is less than the number of members or initializer list is completely empty, the remaining members are initialized by empty lists, in accordance with the usual list-initialization rules (which performs value-initialization for non-class types and non-aggregate classes with default constructors, and aggregate initialization for aggregates).

所以 data 的所有元素都是 value initialized ，对于 uint32，它们将是 zero-initialized最后。

otherwise, the object is zero-initialized.