c++ segmentation fault in linkedlist [closed] - c++

Question

Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers.
This question appears to be off-topic because it lacks sufficient information to diagnose the problem. Describe your problem in more detail or include a minimal example in the question itself.
Closed 8 years ago.
Improve this question
I created a program for my homework that deals with linked lists. It ran fine before i entered a number and then it crashed on me giving me a segmentation fault error.
I know what that means but i cannot find the the issue.
Take a look and see if you could help me out! Thanks!
#include <iostream>
using namespace std;
struct node //node structure
{
int number;
node *next;
};
bool isempty(node *head);
char menu();
void first(node *&head, node *&last, int number );
void insert(node *&head, node *&last, int number);
void remove(node *&head, node *&last);
void shownode(node *current);
bool isempty(node *head)
{
if(head = NULL)
return true;
else
return false;
}
char menu()
{
char choice;
cout<<"choose and option:"<<endl;
cout<<"1. Add Node."<<endl;
cout<<"2. Remove Node."<<endl;
cout<<"3. Show Node List."<<endl;
cout<<"4. Exit Program."<<endl;
cin>>choice;
return choice;
}
void first(node *&head, node *&last, int number ) //adding first
{
node *temp =new node;
temp->number = number;
temp->next = NULL;
head = temp;
last = temp;
}
void insert(node *&head, node *&last, int number)//adding more
{
if(isempty(head))
first(head, last, number);
else
{
node *temp =new node;
temp->number = number;
temp->next = NULL;
last->next = temp;
last = temp;
}
}
void remove(node *&head, node *&last)//destructor
{
if(isempty(head))
cout<<"List is empty."<<endl;
else if (head == last)
{
delete head;
head == NULL;
last == NULL;
}
else
{
node *temp = head;
head = head->next;
delete temp;
}
}
void shownode(node *current)
{
if (isempty(current))
cout<<"list is empty"<<endl;
else
{
cout<<"Nodes in list:"<<endl;
while(current != NULL)
{
cout<<current->number<<endl;
current = current->next;
}
}
}
int main()
{
node *head = NULL;
node *last = NULL;
char choice;
int number;
do{
choice = menu();
switch(choice)
{
case '1': cout<<"inert number:"<<endl;
cin>>number;
insert(head, last, number);
break;
case '2': remove(head, last);
break;
case '3': shownode(head);
break;
default: cout<<"Exit";
}
}while(choice != '4');
return 0;
}
This is the error i got:
choose and option:
1. Add Node.
2. Remove Node.
3. Show Node List.
4. Exit Program.
1
inert number:
44
RUN FINISHED; Segmentation fault: 11; real time: 2s; user: 0ms; system: 0ms

Answer 1

First, this line of code,
if(head = NULL)
should be,
if(head == NULL)

Answer 2

No idea if you are misunderstanding '=' and '==', '=' for assign value and '==' judge if equal.
In bool isempty(node *head) function
if(head = NULL) => if (head == NULL)
In remove(node *&head, node *&last) function
else if (head == last)
{
delete head;
head == NULL;
last == NULL;
}
should be
else if (head == last)
{
delete head;
head = NULL;
last = NULL;
}