Question

我有一个看起来像这样的课程：

class myTreeNode
{
     public:   
        char Data;
        myTreeNode *childA = NULL;   //A's always go in child1
        myTreeNode *childT = NULL;   //T's always go in child2
        myTreeNode *childC = NULL;   //c's always go in child3
        myTreeNode *childG = NULL;   //G's always go in child4
};

然而，当我去分配Data一个值时，我收到一个seg错误。我这样做：

root->childT->Data = p_data;

其中p_data是char = t，而root是由myTreeNode *root = new myTreeNode;创建的指针。为什么在分配Data值时会出现seg错误？它与执行char Data = 't'只是一样吗？

Answer 1

您的孩子没有指向任何记忆位置。您只为根节点创建了一个新实例。您正在获取段错误，因为您正在取消引用空指针。

例如：

class myTreeNode
{
public:
  char Data;
  myTreeNode *childA = NULL;   //A's always go in child1
  myTreeNode *childT = NULL;   //T's always go in child2
  myTreeNode *childC = NULL;   //c's always go in child3
  myTreeNode *childG = NULL;   //G's always go in child4
};

int main()
{
  // allocate memory
  myTreeNode *root = new myTreeNode;
  root->childT = new myTreeNode; // allocate child

  root->childT->Data = 'a';

  // delete allocated memory
  delete root->childT;
  delete root;
  return 0;
}

为什么要分配一个＆＃39; char＆＃39;到了一个＆＃39; char＆＃39;给出一个段错误？ C ++

1 个答案: