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編輯：繼承人更新的插入代碼。我會盡力斷言，但看我還是犯了一個錯誤鏈表分段錯誤。我猜我在這裏做指針錯誤
bool SortedList::insert(Student *s){
bool inList = false;
// create an iterator for the list
ListNode *current = head;
// create a new ListNode for the student to be added
ListNode *addition = new ListNode();
// initialize addition to the student and the next to NULL
addition->student = s;
addition->next = NULL;
//while current is not at the end of the list
while(current != NULL){
// if the iteration's ID is equal to the given ID return
// false and delete the ListNode addition
if(current->student->getID() == addition->student->getID()){
delete addition;
return false;
// else if the next student ID in the list is greater than
// the given ID break the while loop
}else if(current->next != NULL && current->next->student->getID() > addition->student->getID()){
inList = true;
break;
}
// otherwise set current to the next student in the list
current = current->next;
}
// if current is at the end of the list and student wasn't found, set
// current next to addition
if(!inList){
current->next = addition;
// else set addition next to current next next and current next to addition
}else{
addition->next = current->next;
current->next = addition;
}
// return true regardless as the student has been added
return true;
}
我已經遇到一些麻煩我一直對這個基本linkedlist.cpp文件。我猜測我可能使用指針錯誤或沿着這些線路。主文件是作爲一個對象文件給出的，所以我不能看它，出於某種原因，我只想測試插入方法（我睡眠非常低並掙扎）。無論如何，我猜在插入方法的地方我引用NULL錯誤，但我不知道在哪裏。
錯誤：段錯誤（核心轉儲） 注：在運行插入
#include <iostream>
#include "SortedList.h"
using namespace std;
/**
* zero argument constructor - initializes an empty list
*/
SortedList::SortedList() : head(NULL){}
/**
* If a student with the same ID is not already in the list, inserts
* the given student into the list in the appropriate place and returns
* true. If there is already a student in the list with the same ID
* then the list is not changed and false is returned.
*
* @param *s a given pointer to a student
* @return boolean value based on whether the student was inserted or not
*/
bool SortedList::insert(Student *s){
// create an iterator for the list
ListNode *current = head;
// create a new ListNode for the student to be added
ListNode *addition = new ListNode();
// initialize addition to the student and the next to NULL
addition->student = s;
addition->next = NULL;
//while current is not at the end of the list
while(current != NULL){
// if the iteration's ID is equal to the given ID return
// false and delete the ListNode addition
if(current->student->getID() == addition->getID()){
return false;
delete addition;
// else if the next student ID in the list is greater than
// the given ID break the while loop
}else if(current->next->student->getID() > addition->getID()){
break;
}
// otherwise set current to the next student in the list
current = current->next;
}
// if current is at the end of the list and student wasn't found, set
// current next to addition
if(current == NULL){
current->next = addition;
// else set addition next to current next next and current next to addition
}else{
addition->next = current->next->next;
current->next = addition;
}
// return true regardless as the student has been added
return true;
}
/**
* Searches the list for a student with the given student ID. If the
* student is found, it is returned; if it is not found, NULL is returned.
*
* @param studentID the given studentID to find in the list
* @return a pointer to a the student found or NULL if the student isn't found
*/
Student * SortedList::find(int studentID){
// create iterator for the list
ListNode *current = head;
// while not at the end of the list iterate
while(current != NULL){
// if the current student ID equals the given student ID return
// the student
if(current->student->getID() == studentID){
return current->student;
}
// otherwise continue iterating
current = current->next;
}
// if not found then return NULL
return NULL;
}
/**
* Searches the list for a student with the given student ID. If the
* student is found, the student is removed from the list and returned;
* if no student is found with the given ID, NULL is returned.
*
* @param studentID the given student ID to be removed from the list
* @return a pointer to the student that was removed or NULL if the student
* wasn't found
*/
Student * SortedList::remove(int studentID){
// create iterator for the list
ListNode *current = head;
// create the to hold the value ahead of the iterator
ListNode *currentNext;
// create to hold the removed student
Student *remove;
// while current is not at the end of the list iterate
while(current != NULL){
// set currentNext to the value ahead of iterator
currentNext = current->next;
// if its ID equals the given ID
if(currentNext->student->getID() == studentID){
// set remove to the student removing
remove = currentNext->student;
// set current next to currentNext next
// (current next next)
current->next = currentNext->next;
//delete the removed ListNode
delete currentNext;
//return the removed student
return remove;
}
}
//if the student wasn't found return NULL
return NULL;
}
/**
* Prints out the list of students to standard output. The students are
* printed in order of student ID (from smallest to largest), one per line
*/
void SortedList::print() const{
//create iterator for list
ListNode *current = head;
//while current is not at the end of the list iterate
while(current != NULL){
// print each individual student and end line
current->student->print();
cout << endl;
//iterate the list
current = current->next;
}
}
積極使用斷言來幫助縮小問題自己 –