Question

在MS Visual C ++ 2010 SP1中，此代码崩溃：

#include "stdafx.h"

#include <functional>
#include <iostream>
//#include <vector>

int a = 0;

int _tmain(int argc, _TCHAR* argv[]) {
    // this way it works:
    //std::vector<std::function<void ()>> s;
    //s.push_back([]() { a = 1; });
    //s.push_back([]() { a = 2; int b = a; });

    std::function<void ()> s[] = { 
        []() { a = 1; },
        []() {
            a = 2;

            // Problem occurs only if the following line is included. When commented out no problem occurs.
            int b = a;
        }
    };

    int counter = 0;
    for (auto it = std::begin(s); it != std::end(s); ++it) {
        ++counter;
        (*it)();
        std::wcout << counter << L":" << a << std::endl;
    }

    return 0;
}

当构造第二个数组元素时，它会破坏第一个数组元素。

这是编译器中的错误还是我做过C ++ 11标准不支持的事情？

修改

此代码适用于gcc-4.5.1：

#include <functional>
#include <iostream>
//#include <vector>

int a = 0;

int main(int argc, char* argv[]) {
    // this way it works:
    //std::vector<std::function<void ()>> s;
    //s.push_back([]() { a = 1; });
    //s.push_back([]() { a = 2; int b = a; });

    std::function<void ()> s[] = { 
        []() { a = 1; },
        []() {
            a = 2;

            // Problem occurs only if the following line is included. 
            //When commented out no problem occurs.
            int b = a;
        }
    };

    int counter = 0;
    ++counter;
    s[0]();
    std::wcout << counter << L":" << a << std::endl;
    ++counter;
    s[1]();
    std::wcout << counter << L":" << a << std::endl;

    return 0;
}

Answer 1

这是编译器错误。您的代码没有任何问题。

您的程序使用Visual C ++ 11 Beta编译并运行时没有错误，因此该错误似乎已为即将发布的编译器修复。

Answer 2

捕获位在哪里？如果你想修改一个，你不需要在第一个lambda的开头有[＆amp; a]吗？

[&a]() { a = 1; },

http://en.wikipedia.org/wiki/Anonymous_function#C.2B.2B

std :: function在堆栈中的数组中使用时崩溃

2 个答案: