[英]segfault to a null pointer C++
WordBinaryTree::WordBinaryTree()
{
//RootNode is a private WordNode* of WordBinaryTree()
RootNode = 0; //just to set it to null...
}
void WordBinaryTree::AddNode(WordNode node)
{
//RootNode is WordNode*, should be null the first time through
WordNode* currNode = RootNode;
if (!currNode)
{
currNode = new WordNode();
currNode->Value = node.Value;
currNode->Word = node.Word;
RootNode = currNode;
return;
}
while (1)
{
if (currNode->Value > node.Value)
//other code here......
I'm not quite sure what in the world is wrong with my code. 我不太确定我的代码到底出了什么问题。 I've searched online and nothing is coming up with a solution.
我在网上搜索过,没有解决方案。 WordNode is a type struct and RootNode is simply a pointer to that.
WordNode是类型struct,而RootNode只是指向它的指针。 I never set new to RootNode, so it's simply a null pointer the first time this runs through.
我从来没有为RootNode设置new,因此它第一次运行时只是一个空指针。 However, when I try to check if it's null (via currNode), it keeps coming up false and saying it's not null.
但是,当我尝试检查它是否为空(通过currNode)时,它不断出现错误并说它不为空。 Therefore, that first if statement never goes through.
因此,第一个if语句永远不会通过。 This causes a segfault when the if statement in the while loop happens because it's trying to get a value from a null pointer.
当while循环中的if语句发生时,这会导致段错误,因为它试图从空指针获取值。
Why is this happening? 为什么会这样呢? I tried valgrind but it just tells me that there's no malloc/free/etc.
我尝试了valgrind,但它只是告诉我没有malloc / free / etc。 via the address where RootNode is at.
通过RootNode所在的地址。 I know that!
我知道! I'm trying to make a new if it's null (via that if statement) but it just keeps coming up as false, as if the RootNode isn't really null.
我正在尝试创建一个新的是否为空(通过该if语句),但它一直显示为假,好像RootNode并非真正为空。 So what do I do?
那我该怎么办?
be sure you have initialized your RootNode
to null before: 确保在以下情况下已将
RootNode
初始化为null:
WordNode* RootNode=NULL;
if this is done, be sure that this constructor is being called before and that you operate on initialized instance 如果完成此操作,请确保在此构造函数之前被调用,并且您对初始化的实例进行操作
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