C 内存泄漏是由结构向量引起的

c++ memory leak caused by vector of structs

本文关键字：向量 结构 内存 泄漏      更新时间：2023-10-16

由指示行引起的内存泄漏。" pendingsendreqs.push_back（＆amp; f）;''在sendreq（）方法中。我是C 的新手，因此我似乎无法弄清楚为什么发生内存泄漏。内存泄漏的大小为16字节。

class Station {
    struct Frame {
        enum { Token, Data, Ack } type;                  // type of frame
        unsigned int src;                                // source id
        unsigned int dst;                                // destination id
        unsigned int prio;                               // priority
    } frame;
    unsigned int stnId;
    static unsigned int requests;                        // total send requests (if needed)
    void data( Frame frame );                            // pass frame
    void main();                                         // coroutine main
    Station *nextStation;
    vector<Frame*> pendingSendReqs;
  public:
    Station( unsigned int id ) : stnId(id) { }
    ~Station() {
        for (int i = 0; i < pendingSendReqs.size(); i++) {
            delete pendingSendReqs.at(i);
            cout << "~: " << pendingSendReqs.at(i) << endl;
        }
    }
    //unsigned int getId() { return stnId; }
    void setup( Station *nexthop ) {                     // supply next hop
        //*nexthop is the object
        nextStation = nexthop;
        //cout << "size: " << sizeof(*nexthop) << endl;
    }
    void sendreq( unsigned int round, unsigned int dst, unsigned int prio ) { // store send request
        Frame f;
        f.type = Frame::Data;
        f.src = stnId;
        f.dst = dst;
        f.prio = prio;

        pendingSendReqs.push_back(&f); //MEMORY LEAK CAUSED BY THIS LINE
    }
    void start();                                        // inject token and start
};

这不是内存泄漏

pendingSendReqs.push_back(&f);

这是未来的未定义行为。您正在存储本地变量的地址。在函数范围之外，将这些指针之一降低引用的任何尝试都是不确定的行为。

您必须问自己是否真的需要指针的向量。如果您不知道答案，那么您可能不知道。

您正在将指针存储到本地变量上，该变量将在向量内部自动被破坏。这是非法的。

 vector<Frame*> pendingSendReqs;
 // this is a vector of pointers to struct and not a vector of structs
void sendreq( unsigned int round, unsigned int dst, unsigned int prio ) {
    Frame f;     // this automatic variable will get destroyed when sendreq returns
    f.type = Frame::Data;
    f.src = stnId;
    f.dst = dst;
    f.prio = prio;

    pendingSendReqs.push_back(&f); //MEMORY LEAK CAUSED BY THIS LINE
    // because you're going to hold on to this address which will mean
    // nothing when this function returns
}

您打算这样做的方式是：

vector<Frame> pendingSendReqs;

和内部sendreq：

pendingSendReqs.push_back(f); // store the object's copy instead of it's address so that it outlives the life of this local

void sendreq（未签名的int圆，未签名的int dst，unsigned int prio）

结束，

您的矢量pendingsEndreqs将包含被消除的变量（因为是局部变量），并且将包含垃圾。

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