如何通过指针打印数组

Question

我们的老师给了这个代码，我们需要让这个代码运行起来。

如何打印数组中的值？

cout << wizardsCollection->birthYear;

是 returns 我给的但是 wizardsCollection->nameSurname returns 空值。

这是代码的其余部分：

struct Wizard {
    string nameSurname;
    int birthYear;
    string hairColour;
};

struct Wizard *createWizards() {
    Wizard wizardsCollection[3];

    for (int index = 0; index < *(&wizardsCollection + 1) - wizardsCollection; index = index + 1) {
        wizardsCollection[index].nameSurname = "Name and surname of " + index;
        wizardsCollection[index].birthYear = 0;
        wizardsCollection[index].hairColour = "Hair colour of " + index;
    }

    return wizardsCollection;
}

int main()
{
    Wizard *wizardsCollection = createWizards();
    cout << wizardsCollection->nameSurname;
}

Answer 1

你这里有一个大问题。 wizardsCollection 在堆栈上创建。一旦函数 returns，堆栈内存就消失了。您的指针将指向空 space。为此，您需要使用 std::vector 来管理内存。

#include <iostream>
#include <string>
#include <vector>

struct Wizard {
    std::string nameSurname;
    int birthYear;
    std::string hairColour;
};

void createWizards(std::vector<Wizard> & wizardsCollection) {
    wizardsCollection.clear();
    for (int index = 0; index < 3; index++ ) {
        wizardsCollection.push_back(Wizard({
            "Name and surname of " + std::to_string(index),
            0,
            "Hair colour of " + std::to_string(index)
        }));
    }
}

int main()
{
    std::vector<Wizard> wizardsCollection;
    createWizards(wizardsCollection);
    std::cout << wizardsCollection[0].nameSurname << "\n";
}

还有其他方法可以做到这一点，但这是模拟你所拥有的。

如何通过指针打印数组

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