c++ - Inserting data in a singly link list by specifying the nth node position -

so logic goes this: suppose link list consists of (6,7,8) data , pass insert(1,5),so list (5,6,7,8). on insert(3,2) link list (6,7,2,8).

i tried compiling below code gives me error stating-

undefined reference main '-start'

i tried debugging,even searching answers found no help.kindly suggest solution.any further suggestions , bug fixes shall welcomed. (i have used codepad compiling)

#include<iostream>  using namespace std; class link_no {     struct node     {         int data;         node *next;     };      void insert(int n,int d,node *head)     {         node *temp=new node();         temp->data=d;         temp->next=null;         node *temp1;          if(n==1)         {             temp->next=head;             head=temp;             return;         }         else             temp1=head;         {             for(int i=0;i<n-1;i++)             {                 temp1=temp1->next;             }             temp->next=temp1;             temp1=temp;        }     }     void print(node *start)     {         node *temp=start;         while(temp!=null)         {             cout<<temp->data<<endl;             temp=temp->next;         }     }     int main()     {         node *head=null;         link_no o1;         o1.insert(1,5,head);         o1.insert(2,7,head);         o1.insert(1,9,head);         o1.print(head);         return 0;     } } 

the following compiles

#include<iostream>  using namespace std; class link_no {     private:     struct node     {         int data;         node *next;     };      node *head;     public:       link_no(){         head = nullptr;     }      void insert(int n,int d)     {         node *temp=new node();         temp->data=d;         temp->next=null;         node *temp1;          if(n==1)         {             temp->next=head;             head=temp;             return;         }         else             temp1=head;         {             for(int i=0;i<n-1;i++)             {                 temp1=temp1->next;             }             temp->next=temp1;             temp1=temp;        }     }      void print()     {         node *temp=head;         while(temp!=null)         {             cout << "data " << temp->data<<endl;             temp=temp->next;         }     }   };      int main()     {         link_no o1;         o1.insert(1,5);         o1.insert(2,7);         o1.insert(1,9);         o1.print();         return 0;     } 

it not want yet prints out 5 , 9 data need debug more.

edit: suggest take paper , pen , manually try you're doing in else since there going wrong there.

if can't find out on own following works me, haven't tried testing extreme cases yet.

#include<iostream>  using namespace std; class link_no {     private:     struct node     {         int data;         node *next;     };      node *head;     public:       link_no(){         head = nullptr;     }      void insert(int n,int d)     {         node *temp=new node();         temp->data=d;         temp->next=null;         node *temp1;          if(n==1)         {             temp->next=head;             head=temp;             return;         }         else         {             cout << "foo" << endl;             temp1=head;             for(int i=1;i<n-1;i++)             {                 temp1=temp1->next;             }             node *temp2 = temp1->next;             temp1->next = temp;             temp->next=temp2;        }     }      void print()     {         node *temp=head;         cout << "link" << endl;         while(temp!=null)         {             cout << "data " << temp->data<<endl;             temp=temp->next;         }     }   };      int main()     {         link_no o1;         o1.insert(1,5);         o1.print();         o1.insert(2,7);         o1.print();         o1.insert(1,9);         o1.insert(2,6);         o1.print();         return 0;     }