在C ++ 14中支持std :: cbegin（） [英] Support of std::cbegin() in C++14

问题描述

Scott Mayers的 Effective Modern C ++中的第13条指出，与迭代器相比，const_iterators更受欢迎。我同意，但我也想使用非成员函数而不是成员函数。根据这本书，应该有一个非成员函数 std :: cbegin（）和 std :: cend（）在C ++ 14中。

Item 13 from Scott Mayers' "Effective Modern C++" states to prefer const_iterators over iterators. I agree but I also want to use non-member functions rather than member functions. According to the book there should be a non-member function std::cbegin() and std::cend() in C++14.

要使用此功能，我刚刚安装了gcc版本4.9.2，并使用标志 -std = c ++ 14 。在我尝试使用 std :: cbegin（）之前，它似乎一直可以编译。我开始寻找对此功能的支持，但找不到任何相关信息。例如，在 gnu onlinedocs状态中，甚至没有提到该功能。

To make use of this functions I just installed gcc version 4.9.2 and compiled with the flag -std=c++14. It seems to compile until I try to use std::cbegin(). I start searching for the support for this function but couldn't find anything about it. For example, at gnu onlinedocs status the function isn't even mentioned.

我的问题是，将 std :: cbegin（）和 std :: cend（）确实在c ++ 14中受支持，或者这是书中的错误吗？如果这将是C ++ 14功能，是否有已经支持这些功能的编译器？何时gcc会支持这些功能？

My question is, will std::cbegin() and std::cend() really be supported in c++14 or is this a mistake in the book? If it will be a C++14 feature, are there compilers which already support these functions and when will gcc support it?

SO中关于 begin（），但是这些问题与成员函数或constexpr-ness有关，而不与非成员变量的支持有关。

There are many questions at SO about begin() but these questions are about the member functions or about the constexpr-ness and not about the support of the non-member variant.

推荐答案

GCC 4.9对C ++ 14的支持是实验性的，并不完整。但是这里，您可以看到

GCC 4.9's support for C++14 is experimental and incomplete. But here, you can see that

全局函数cbegin，cend，rbegin，rend，crbegin和crend用于对容器，数组和初始化列表的范围访问。

global functions cbegin, cend, rbegin, rend, crbegin, and crend for range access to containers, arrays and initializer lists.

$在GCC 5.1中添加了b
$ b

。

were added in GCC 5.1.

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