C++11 在 Visual Studio 2017 中可用吗？
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Is C++11 available in Visual Studio 2017?
提问by user3344484
I am currently using Visual Studio Community 2017. From looking at the C++ Language Standards in the project properties, they only provide C++14 and C++17. Since my code was completed for a previous assignment using a compiler for C++11, I am unable to run my code using functions such as stoi. My question is if there is a way to add C++11 to the language standards for C++?
我目前使用的是 Visual Studio Community 2017。从项目属性中的 C++ Language Standards 来看，他们只提供 C++14 和 C++17。由于我的代码是使用 C++11 的编译器完成的先前分配的代码，因此我无法使用诸如 stoi 之类的函数运行我的代码。我的问题是是否有办法将 C++11 添加到 C++ 的语言标准中？
I am creating a DLL for a GUI, my initializations are:
我正在为 GUI 创建一个 DLL，我的初始化是：
#include <string>
#include "stdafx.h"
using namespace std;
Here I am creating a fraction class, the main errors follow in the ifstream:
在这里，我创建了一个分数类，主要错误出现在 ifstream 中：
istream& operator>>(istream& in, Fraction& f) {
string number;
in >> number; //read the number
size_t delimiter = number.find("/"); //find the delimiter in the string "/"
if (delimiter != string::npos) { //if delimiter is not empty
int n = stoi(number.substr(0, delimiter)); //set numerator from string to integer before the "/"
int d = stoi(number.substr(delimiter + 1)); //set denominator from string to integer after the "/"
if (d == 0) { //if denominator is 0
throw FractionException("Illegal denominator, cannot divide by zero."); //illegal argument throw
}
else if (n == 0 && d != 0) { //numerator is 0, then set values as zero fraction
f.numVal = 0;
f.denVal = 1;
}
else { //set the values into the fraction and normalize and reduce fraction to minimum
f.numVal = n;
f.denVal = d;
f.normalizeAndReduce(f.numVal, f.denVal);
}
}
else { //else if there is no delimiter it would be a single integer
f.numVal = stoi(number);
f.denVal = 1;
}
return in;
}
I am getting the following errors:
我收到以下错误：
C2679: binary '>>': no operator found which takes a right-hand operator of type 'std::string"
C3861: 'stoi' identifier not found
This method worked perfectly fine in eclipse, not sure what I am doing wrong.
这种方法在 eclipse 中工作得很好，不知道我做错了什么。
回答by Chuck Walbourn
The Visual C++ 2017 compiler is C++11/C++14 compliant with a few specific exceptions:
Visual C++ 2017 编译器符合 C++11/C++14，但有一些特定的例外：
- Expression SFINAEis implemented, but not complete.
- Full C99 preprocessor support is limited due to some bugs with variadic macros
- Two phase name lookup is in VS 2017 (15.3 update) but is incompleteand only active when using /permissive-
- 表达式 SFINAE已实现，但尚未完成。
- 由于可变参数宏的一些错误，完整的 C99 预处理器支持受到限制
- 两阶段名称查找在 VS 2017（15.3 更新）中，但不完整且仅在使用/permissive-时才处于活动状态
The compiler does not offer a specific C++11 mode and defaults to C++14, but that standard is fully inclusive of C++11. C++17 support is in progress, and requires you use the /std:c++17or /std::c++latestswitch.
编译器不提供特定的 C++11 模式并默认为 C++14，但该标准完全包含 C++11。C++17 支持正在进行中，需要您使用/std:c++17或/std::c++latest开关。
std::stoirequires you include the appropriate header, specifically <string>>Either you forgot to include that header -or- you didn't deal with the namespaceresolution (either explicitly as std::or via using namespace std;)
std::stoi要求您包含适当的标题，特别是<string>>您忘记包含该标题 - 或者 - 您没有处理namespace分辨率（明确作为std::或通过using namespace std;）
See C++17 Features And STL Fixes In VS 2017 15.3for the latest status of C++11/C++14/C++17 standards conformance as of the VS 2017 (15.3 update)
请参阅VS 2017 15.3中的C++17 特性和 STL 修复，了解截至 VS 2017（15.3 更新）的 C++11/C++14/C++17 标准一致性的最新状态
UPDATED:Now that you have posted your code, I see that the problem has nothingto do with which standard is supported. Your problem is that you don't know the secrets of how Precompiled Headers work.
更新：既然您已经发布了代码，我发现问题与支持的标准无关。你的问题是你不知道预编译头如何工作的秘密。
Change:
改变：
#include <string>
#include "stdafx.h"
to:
到：
#include "stdafx.h"
#include <string>
-or- add #include <string>to the precompiled header stdafx.hdirectly.
- 或 -直接添加#include <string>到预编译头stdafx.h。
See Creating Precompiled Header Files
请参阅创建预编译头文件
回答by AliReza
回答by Mike Diack
As an update to this, VS 2017, Update 9.4 (releasd Dec 2018) is now fully C++17 compliant.
作为对此的更新，VS 2017 更新 9.4（2018 年 12 月发布）现在完全符合 C++17。
回答by davidbak
C++ is an evolving standard - after 2003 there was 2011 (C++11) then 2014 (C++14) and now we have 2017 (C++17) and we're working towards 2020 (C++20). They're upward compatible.
C++ 是一个不断发展的标准 - 2003 年之后是 2011 年（C++11）然后是 2014 年（C++14），现在我们有了 2017 年（C++17），我们正朝着 2020 年（C++20）努力。它们向上兼容。
Look herefor Microsoft Visual C++ support for the various standards.
看看这里为各种标准的Microsoft Visual C ++的支持。
