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#include <iostream>
#include <string>
using namespace std;
class LinkedList{
private:
struct node{
int data;
node* next;
};
node* head;
node* iterator_current;
public:
LinkedList();
void add(const int &);
int remove();
bool isEmpty() const;
bool more();
int next();
void setiterator();
void insertbeforecurrent( const int& );
bool delete_current( int& );
};
LinkedList::LinkedList(){
head = NULL;
iterator_current = NULL;
}
void LinkedList:: add( const int& data ){
node* tmp;
node* curr;
tmp = new node;
tmp->data = data;
tmp->next = NULL;
if( head != NULL ){
curr = head;
while( curr->next ){
curr = curr->next;
}
curr->next = tmp;
}
else
head = tmp;
}
bool LinkedList::isEmpty()const{
if( head == NULL )
return true;
else
return false;
}
int LinkedList::remove(){
node* tmp;
int data;
data = head->data;
tmp = head;
head = head->next;
delete tmp;
return data;
}
bool LinkedList::more(){
if( iterator_current != NULL )
return true;
else
return false;
}
void LinkedList::setiterator(){
iterator_current = head;
}
int LinkedList::next(){
int tmp = iterator_current->data;
iterator_current = iterator_current->next;
return tmp;
}
bool LinkedList::delete_current( int& retdata ){
node* curr;
node* prev;
curr = head;
prev = NULL;
if( iterator_current == NULL )
return false;
while( curr != iterator_current ){
prev = curr;
curr = curr->next;
}
if( curr == NULL )
return false;
if( prev ){
prev->next = curr->next;
retdata = curr->data;
delete curr;
return true;
}
else{
head = curr->next;
retdata = curr->data;
delete curr;
return true;
}
}
void LinkedList::insertbeforecurrent( const int& data ){
node* tmp;
tmp = new node;
tmp->data = data;
tmp->next = NULL;
node* curr;
node* prev;
curr = head;
prev = NULL;
while( curr != iterator_current ){
prev = curr;
curr = curr->next;
}
if( prev == NULL ){
head = tmp;
}
else
prev->next = tmp;
tmp->next = curr;
}
int main(){
LinkedList d1;
cout << "Enter number : ";
int number;
while( cin >> number ){
d1.add( number );
cout << "Enter number : ";
}
d1.setiterator();
int value = d1.next();
int foot = 1000;
int foot1 = 50;
d1.insertbeforecurrent( foot );
d1.setiterator();
while( d1.delete_current( foot1 ) )
while( d1.more() ){
int x = d1.next();
cout << "Node contain : " << x << endl;
}
system( "pause" );
return 0;
}
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why my main delete current cannot work?
the problem is that you don't reset iterator_current
to a something valid. After the call to delete_current()
it points to an invalid node
so i have to add
d1.setiterator()
back?
or?
i wan to delete certain value only
In delete_current()
you may call next()
after the while loop.
Note that calling next()
is somewhat dangerous since it would crash if iterator_current
doesn't point to a valid node
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