c++ - 单链表不工作(C++)

Question

以下代码构建正确，但在我运行时导致程序崩溃。有人可以告诉我它有什么问题吗？我怀疑 DeleteNode 函数有问题。

#include <iostream>
#include <cstdlib>

using namespace std;

class list {
private:
    typedef struct node {
        int data;
        node* next;
    }* nodePtr;  //this means that 'nodePtr' will mean a pointer to the struct node

nodePtr head;
nodePtr current;
nodePtr temp;

public:
list() {  //constuctor
    head = NULL;
    current = NULL;
    temp = NULL;
};

void AddNode(int addData)  //to add a particular data value
{
    nodePtr n= new node;
    n->next = NULL;
    n->data = addData;

    if (head != NULL) {  //if a list is already set up
        current = head;
        while (current->next != NULL) {  //to get to the last node in the list
            current = current->next;
        }
        current->next = n;
    }
    else {  // if list is not created
        head = n;  //new node is front of the list
    }
}

void DeleteNode(int delData)  //to delete a particular data value
{
    nodePtr delPtr = NULL;
    temp = head;
    current = head;

    while (current != NULL  && current->data!=delData) {  //pass through whole list && find value
        temp = current;
        current = current->next;
    }

    if (current = NULL) {  //data value not found in list
        cout << delData << " was not in the list." << endl;
        delete delPtr;  //to free up memory space
    }
    else {
        delPtr = current;
        current = current->next;
        temp->next = current;  //to reconnect list

        if (delPtr == head) {
            head = head->next;
            temp = head;
        }

        delete delPtr;
        cout << "The value " << delData << "was deleted." << endl;
    }
}

void PrintList()  //to print all the data values
{
    current = head;

    while (current != NULL) {  //to go through the data valued of the list
        cout << current->data << endl;
        current = current->next;
    }
}

};



int main()
{
    list Shahzad;

    Shahzad.AddNode(2);
    Shahzad.AddNode(78);
    Shahzad.AddNode(28);
    Shahzad.AddNode(2398);

    Shahzad.DeleteNode(78);
    Shahzad.PrintList();
    return 0;
}

Answer 1

您的第一个问题是以下行:

if (current = NULL)

此时您实际上是分配 null 给 current。

这实际上应该是:

if (current == NULL)