c++ - 访问冲突读取位置 0xCDCDCDD1

Question

我正在使用 Visual Studio 2013。我收到了 Access violation reading location 0xCDCDCDD1 错误。引用资料来自 Wikipedia: Magic Numbers , here , 和 this question告诉我我正在使用未初始化的指针。我认为问题出在我正在使用的 malloc 函数上，尽管我确实引用了 CPlusPlus在使用它之前先文档。

我的代码:

#include "SingleNode.h"
#include "SingleList.h"
#include <iostream>
SingleList::SingleList() {}
SingleList::~SingleList() {}
...
    void SingleList::addHead(int value){
    ISingleNode *temp1 = (ISingleNode *)malloc(sizeof(SingleList));
    head = NULL;
    temp1->setValue(value);
    temp1->setNext(head->getNext());
    if (!head->getNext())
    {
        head = temp1;
    }
    else
    {
        temp1->setNext(head->getNext());
        head = temp1;
    }
}

    ...

错误在行 temp1->setValue(value);

setValue(int value) 函数包含在此处:

#include "SingleNode.h"
SingleNode::SingleNode() {}
SingleNode::~SingleNode() {}
void SingleNode::setValue(int value){
    this->value = value;
}
int SingleNode::getValue(){
    return value;
}
ISingleNode * SingleNode::getNext(){
    return next;
}
void SingleNode::setNext(ISingleNode * next){
    this->next = next;
}

单节点.h:

#pragma once
#include "Interfaces01.h"
class SingleNode :public ISingleNode{
private:
    int value;
    ISingleNode * next = NULL;
public:
    SingleNode();
    ~SingleNode();
    void setValue(int value);
    int getValue();
    ISingleNode * getNext();
    void setNext(ISingleNode * next);
};

单个列表.h:

#pragma once
#include "Interfaces01.h"
class SingleList :public ISingleList{
private:
    int value;
    ISingleNode * head=NULL;
    ISingleNode * temp=NULL;
    ISingleNode * next=NULL;
    ISingleNode * temp1;
public:
    SingleList();
    ~SingleList();
    ISingleNode * getHead();
    void setHead(ISingleNode * head);
    void addHead(int value);
    void orderSort2();
    void orderSort3();
    void sequenceOrderSort();
    void reverse();
    ISingleNode * swap(ISingleNode * head, int k);
    ISingleNode * get_node(ISingleNode * head, int k);
};

断行时，调试器向我显示以下值:

Answer 1

1. 改变:

   ISingleNode *temp1 = (ISingleNode *)malloc(sizeof(SingleList));
   

   进入:

   ISingleNode *temp1 = new SingleList;
   

2. 您正在访问一个 NULL 指针:

   head = NULL; // set to NULL
   temp1->setValue(value);
   temp1->setNext(head->getNext()); // oops!
   

   你的意思可能是:

   void SingleList::addHead(int value)
   {
       ISingleNode *temp1 = new SingleList;
       temp1->setValue(value);
       temp1->setNext(head);
       head = temp1;
   }