Question

www.un.org/spanish/ga/president <代码>struct的初始化需要图书馆,阵列的初始化也需要图书馆。因此,我需要两个镜子:

std::array<int, 5> a = {{1, 2, 3, 4, 5}};

But most of the example code I have seen only uses one pair of braces:

std::array<int, 5> b = {1, 2, 3, 4, 5};

如何允许这样做,与第一 app相比,它是否有任何好处或缺点?

Answer 1

The benefit is that you have ... less to type. But the drawback is that you are only allowed to leave off braces when the declaration has that form. If you leave off the =, or if the array is a member and you initialize it with member{{1, 2, 3, 4, 5}}, you cannot only pass one pair of braces.

这是因为,如<代码>f({1,2,3,4,><>>> 代码/代码>,有可能会超负荷的模糊之处。但它引起了一些讨论,并产生了一份议题报告。

基本上,<代码>={......}的初始化始终能够像在原始状态中那样排除bra。

int a[][2] = { 1, 2, 3, 4 };

这并不是新的。新的是,你可以忽略<条码>=,但你必须指明所有图书馆。

int a[][2]{ {1, 2}, {3, 4} };

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