Question

我有一个问题要问你。假设我有一个AwesomeData向量，而类AwesomeData包含一个AwesomeData向量。如果我尝试访问第一个向量内的向量，它将无法正常工作。据我所知，这里还不清楚一个更明确的例子：

struct AwesomeData
{
public:
    AwesomeData()
    : beautifulInt(3)
    {}

    int beautifulInt;
    vector<AwesomeData> someVector;
};

int main()
{
    vector<AwesomeData> tata;
    AwesomeData toto;

    toto.someVector.push_back(AwesomeData());
    toto.someVector.push_back(AwesomeData());
    toto.someVector.push_back(AwesomeData());

    tata.push_back(AwesomeData());
    tata.push_back(toto);
    tata.push_back(AwesomeData());


    // So, now tata should containt the data of someVector of toto (3 default    
    // AwesomeData). Instead of that, his capacity is equal to 3, but his
    // size = 0. So, what's wrong ?
    tata = tata[1].someVector;
}

但是，嘿，不是全部！我找到了一个解决方法，但我不知道它为什么会起作用。

struct AwesomeData
{
public:
    AwesomeData()
        : beautifulInt(3)
    {}

    int beautifulInt;
    vector<AwesomeData> someVector;
};

int main()
{
    vector<AwesomeData> tata;
    AwesomeData toto;

    toto.someVector.push_back(AwesomeData());
    toto.someVector.push_back(AwesomeData());
    toto.someVector.push_back(AwesomeData());

    tata.push_back(AwesomeData());
    tata.push_back(toto);
    tata.push_back(AwesomeData());


    // If we use a second vector to temporaly stock the vector of toto,
    // everything work as expected
    vector<AwesomeData> tempVector;

    tempVector = tata[1].someVector;
    tata = tempVector;
}

所以任何人都有想法？

非常感谢

Answer 1

标准容器不允许您使用in-complete类型实例化它们。在您的示例中，当您尝试实例化AwesomeData时，std::vector<AwesomeData>未完全定义。

要实现这一目标，您可以查看boost::container库。

请参阅Boost::container

向量c ++的奇怪行为

1 个答案: