c++ - Is C++11 available in Visual Studio 2017?

Question

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++?

I am creating a DLL for a GUI, my initializations are:

#include <string>
#include "stdafx.h"

using namespace std;

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;
}

I am getting the following errors:

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.

Answer 1

The Visual C++ 2017 compiler is C++11/C++14 compliant with a few specific exceptions:

• Expression SFINAE is implemented, but not complete. (Now complete in VS 2017 (15.7))
• 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- (Now complete in VS 2017 (15.7))

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 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;)

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)

UPDATED: For the latest on Visual C++ conformance, see Microsoft Docs.

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.

Change:

#include <string>
#include "stdafx.h"

to:

#include "stdafx.h"
#include <string>

-or- add #include <string> to the precompiled header stdafx.h directly.

See Creating Precompiled Header Files