我正在尝试实现我的显示功能（在我的main.cc文件中）。但是，当我使用 curr 指针获取 Student 对象上的数据然后遍历列表时，程序核心转储。
MAIN.CC
#include "Node.h"
#include "Student.h"
using namespace std;
void append (Node **, Node *); //append Node to end of list.
void display(Node *); //print linked list.
void input(Student *); //enter new Student object.
void deleteNode(Node **, string); //delete specific Node.
string first;
string mid;
string last;
string ssn;
string age;
int main() {
string flag; //flag checks for delimiter.
string name;
string stuDelete; //name to be deleted.
Student * stuPtr = NULL;
Node * head = NULL;
Node * newPtr = NULL;
do {
stuPtr = new Student;
input(stuPtr);
flag = stuPtr ->getFirst(); //flag = first name
if(stuPtr -> getFirst() == "-") { //"-" is delimiter
cout << "in if statement\n";
delete stuPtr; //no new Student, no more need for
//temporary Student pointer.
stuPtr = NULL;
cout << "checkpoint1" << endl;
}
else {
newPtr = new Node(stuPtr);
append(& head, newPtr);
cout << "checkpoint 2" << endl;
}
} while (first != "-"); //will prompt for more entries unless
//delimiter is detected.
cout << "checkpoint 3" << endl;
display(head); // MY DISPLAY FUNCTION SUCKS
if(head)
cout << "Enter a Student to be deleted" << endl;
while(head) {
cout << "Last name: ";
cin >> stuDelete;
deleteNode(& head, stuDelete);
string reqDelete; // asks if you want to keep deleting.
cout << "Student has been deleted. Delete another? (Y/N)" << endl;
cin >> reqDelete;
if(head != NULL && reqDelete == "Y") {
display(head); //iterates thru linked list
cout << "\nEnter another name to be deleted: \n" << endl;
}
else if(reqDelete != "Y")
cout << "Deletion complete.\n" << endl;
}
if(head)
display(head);
else
cout << "The list is now empty.\n"
<< "=============================" << endl;
return 0;
}
void display (Node * newPtr) {
Node * curr = newPtr;
while(curr != NULL) {
// getData is used to point to the stud info in a node
cout << "{"
<< curr->getData()->getFirst() << ", "
<< curr->getData()->getMiddle() << ", "
<< curr->getData()->getLast()<< ", "
<< curr->getData()->getSocial()<< ", "
<< curr->getData()->getAge()
<< "}" << endl;
curr = curr->getNext(); // move to the next obj, traverse stud data
}
cout << "-----------------------------------------" << endl;
}
我将列出我的Node和Student课程的标题。如果这还不够，请告诉我。
NODE.H
class Node {
public:
Node(); //Default constructor.
Node(Student *); //New constructor.
Student * getData(); //get data on Student object.
void setData(Student *); //set data for Student object.
Node * getNext(); //get the next Node in the linked list.
void setNext(Node * ); //set the next Node in the list.
private:
Student * data; //pointer to current Student data.
Node * next; //pointer within Node to the next Node.
};
#endif
STUDENT.H
class Student {
public:
Student(); //Default constructor;
Student(const string &, const string &, const string &,
const string &, const string &); //New constructor.
//setters
void setName(const string &, const string &, const string &);
void setSocial(const string &);
void setAge(const string &);
//getters
string getFirst();
string getMiddle();
string getLast();
string getSocial();
string getAge();
private:
string stuData[5]; //array of fields for Student data.
};
终端输出
faruki@ubuntu:~/DataStructures/Lab4$ ./a.out
Enter Student information (Enter '-' to exit)
First Name: jesus
Middle Name: h
Last Name: christ
Social: 222222222
Age: 222
==============================
checkpoint 2
Enter Student information (Enter '-' to exit)
First Name: -
Student entry finished.
==============================
in if statement
checkpoint1
checkpoint 3
Segmentation fault (core dumped)
学生班级的建构者
Student::Student() {
stuData[0] = "Firstname";
stuData[1] = "Middlename";
stuData[2] = "Lastname";
stuData[3] = "SSN";
stuData[4] = "##";
}
Student::Student(const string & first, const string & mid,
const string & last, const string & ssn, const string & age) {
setName(first, mid, last);
setSocial(ssn);
setAge(age);
}
NODE CLASS的结构
Node::Node() {
next = NULL; //new Nodes go to the end of the list.
}
Node::Node(Student * tempData) {
data = tempData;
delete tempData;
next = NULL;
}
答案 0 :(得分：1)
nullptr而不是NULL