int（）返回0或任意值？ [英] Does int() return 0 or an arbitrary value?

问题描述

请考虑此代码：

template <typename T>
void f()
{T x = T();}

当 T = int 时， x 等于 0 到任意值？

奖金问题，因此是数组（ T [N] 和 std :: array< T，N> ）这种语法可以留下任意值的内容的唯一类型。

Bonus question: and consequently, are arrays (both T[N] and std::array<T, N>) the only types where such a syntax may leave contents with arbitrary values.

推荐答案

T（）提供值初始化类，联合或数组之外的类型。 （§8.5/ 7 bullet 3）：否则，对象是零初始化的。对于数组，数组的每个元素都是值初始化的。

T() gives value initialization, which gives zero-initialization for a type other than a class, union or array. (§8.5/7 bullet 3): "otherwise, the object is zero-initialized." For an array, each element of the array is value initialized.

对于数组，如果是自动存储类，内容将是任意值，它是静态存储类 - 即，全局（当然，假设你不指定任何初始化）。

For an array, the content will be of an arbitrary value if it's auto storage class, but zero initialized if it's static storage class -- i.e., global (assuming, of course, that you don't specify any initialization).

这篇关于int（）返回0或任意值？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！