Visual Studio 2017中是否提供C ++ 11？ [英] Is C++11 available in Visual Studio 2017?
问题描述
我当前正在使用Visual Studio Community2017。通过在项目属性中查看C ++语言标准，它们仅提供C ++ 14和C ++ 17。由于我的代码已完成使用C ++ 11的编译器进行的先前分配，因此无法使用stoi等功能运行我的代码。我的问题是是否可以将C ++ 11添加到C ++语言标准中？
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++?
我正在为GUI创建DLL，我的初始化是：
I am creating a DLL for a GUI, my initializations are:
#include <string>
#include "stdafx.h"
using namespace std;
在这里我要创建一个分数类，主要错误出现在ifstream中：
Here I am creating a fraction class, the main errors follow in the ifstream:
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;
}
我遇到以下错误：
C2679: binary '>>': no operator found which takes a right-hand operator of type 'std::string"
C3861: 'stoi' identifier not found
此方法在日食时效果很好，不确定我在做什么错。
This method worked perfectly fine in eclipse, not sure what I am doing wrong.
推荐答案
Visual C ++ 2017编译器符合C ++ 11 / C ++ 14，但有一些特定的例外：
The Visual C++ 2017 compiler is C++11/C++14 compliant with a few specific exceptions:
- 表达式SFINAE 已实现，但未完成。
- 由于可变参数宏的某些错误，对C99预处理程序的完全支持有限
- 两阶段名称查找在VS 2017中（15.3更新），但不完整，仅在使用 / permissive-
- Expression SFINAE is 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 incomplete and only active when using /permissive-
编译器不提供特定的C ++ 11模式，默认为C ++ 14，但该标准完全包含C ++ 11。 C ++ 17支持正在进行中，要求您使用 / std：c ++ 17 或 / std :: c ++ latest 开关。
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++17 or /std::c++latest switch.
std :: stoi 要求您包括适当的标头，特别是< string>> 要么您忘记包含该标头，要么-您没有处理命名空间解析（要么显式表示为 std :: 或通过使用命名空间std; ）
std::stoi requires you include the appropriate header, specifically <string>> Either you forgot to include that header -or- you didn't deal with the namespace resolution (either explicitly as std:: or via using namespace std;)
请参见 C VS 2017 15.3中的++ 17功能和STL修复，用于了解自VS 2017起最新的C ++ 11 / C ++ 14 / C ++ 17标准符合性（15.3更新）
See C++17 Features And STL Fixes In VS 2017 15.3 for the latest status of C++11/C++14/C++17 standards conformance as of the VS 2017 (15.3 update)
已更新：：既然您已经发布了代码，我发现问题什么都没有了与支持哪种标准有关。您的问题是您不知道预编译标头如何工作的秘密。
UPDATED: Now that you have posted your code, I see that the problem has nothing to do with which standard is supported. Your problem is that you don't know the secrets of how Precompiled Headers work.
更改：
#include <string>
#include "stdafx.h"
至：
#include "stdafx.h"
#include <string>
-或-添加 #include< string> 直接转到预编译的头文件 stdafx.h 。
-or- add #include <string> to the precompiled header stdafx.h directly.
请参见创建预编译的头文件
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