指向矢量中对象的指针有时指向矢量中不同的对象

但是,当我输出指向Struct2对象的Struct1对象的索引变量时,在某些情况下会返回错误的索引变量。

struct Struct1
{
    size_t index;
    std::vector<size_t> data;
}

struct Struct2
{
    Struct1 *s1;
}

class MyClass
{
    std::vector<Struct1> s1s;
    std::vector<Struct2> s2s;
    size_t propIndex = 0;

    void input(QByteArray &line)
    {
        if (line == "1") {
            for (size_t i = s1s.size(); i <= propIndex; i++) {
                s1s.push_back({ .index = i, .data= {} });
            }
            QByteArrayList list = getList();
            for (auto id : list)  s1s.at(propIndex).data.push_back(id.toULongLong());
        }
        else {
            if (propIndex == s2s.size()) {
                s2s.push_back({ .s1 = nullptr });
            }

            if (line == "2") {
                size_t index = getIndex();
                for (size_t i = s1s.size(); i <= index; i++) {
                    s1s.push_back({ .index = i, .data= {} });
                }
                s2s.at(propIndex).s1 = &s1s.at(index);
            }
        }

        propIndex++;
    }

    QByteArrayList output()
    {
        QByteArrayList output;

        for (auto s2 : s2s) {
            output += QByteArray::number(s2.s1->index) + "\n";
        }

        return output;
    }
}