Question

我正在使用C ++来实现FP-growth算法，但是在使用vector时我遇到了一些错误。这是我的代码：

typedef struct Node
{
    FPData *fpData;
    int childCount;
    struct Node *parent;
    vector<Node*> childs;
}FPNode;

FPNode* FPTree::NewNode(string data, int support)
{
    FPNode *node = (FPNode*) malloc(sizeof(FPNode));
    FPData *fpData = (FPData*) malloc(sizeof(FPData));
    fpData -> data = data;
    fpData -> support = support;
    node -> fpData = fpData;
    node -> childCount = 0;
    node -> parent = NULL;
    return node;
}
void FPTree::InsertFPPath(FPNode* root, list<FPData*> fpDatas)
{
    if(fpDatas.size() <= 0)
    {
        return;
    }
    bool flag = true;
    for(int i = 0; i < root -> childCount; i++)
    {
        FPNode* child = root -> childs[i];
        if(child -> fpData -> data == fpDatas.front() -> data)
        {
           flag = false;
           child -> fpData -> support ++;
           fpDatas.pop_front();
           InsertFPPath(child, fpDatas);
           break;
        }
    }
    if(flag)
    {
        FPData* firstData = fpDatas.front();
        FPNode* newChild = NewNode(firstData -> data, firstData -> support);
        root -> childs.push_back(newChild);   // error at here
        root -> childCount ++;
        fpDatas.pop_front();
        for(int i = 0; i < fpDatas.size(); i++)
        {

            InsertFPPath(newChild, fpDatas);
        }
     }
}

InsertFPPath()是递归方法，第二次迭代时出错：

root -> childs.push_back(newChild)

错误发生在：

 construct(_Up* __p, _Args&&... __args)  // here the __p is null, and __args is right
 {
      ::new((void*)__p) _Up(_VSTD::forward<_Args>(__args)...);
 }

线程队列停在：

#0  0x00000001000050cf in void std::__1::allocator::construct(Node**, Node* const&&&) [inlined] at /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/memory:1673

回溯是：

#0  0x00000001000050cf in void std::__1::allocator::construct(Node**, Node* const&&&) [inlined] at /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/memory:1673
#1  0x00000001000050bc in void std::__1::allocator_traits >::__construct(std::__1::integral_constant, std::__1::allocator&, Node**, Node* const&&&) [inlined] at /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/memory:1600
#2  0x000000010000509c in void std::__1::allocator_traits >::construct(std::__1::allocator&, Node**, Node* const&&&) [inlined] at /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/memory:1453
#3  0x0000000100005079 in std::__1::vector >::push_back(Node* const&) [inlined] at /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/vector:1590
#4  0x0000000100004fa9 in FPTree::InsertFPPath(Node*, std::__1::list >) at /Users/dorothy/ME/USTC/作业/数据挖掘/experiment/FPTree/FPTree/FPTree.cpp:129
#5  0x00000001000051b4 in FPTree::InsertFPPath(Node*, std::__1::list >) at /Users/dorothy/ME/USTC/作业/数据挖掘/experiment/FPTree/FPTree/FPTree.cpp:135**

Answer 1

为包含构造函数的结构（struct或class）或包含具有构造函数的对象的结构分配内存时，则无法使用malloc分配内存。 malloc函数只分配内存，但它不会调用构造函数，在你的情况下，这意味着不会构造childs成员对象，并且使用向量将导致未定义的行为。

在C ++中动态分配内存时，需要使用new运算符：

FPNode *node = new FPNode;
FPData *fpData = new FPData;

矢量推回错误

1 个答案: