C LAB‎ > ‎(Sem2) Data Structures‎ > ‎

Qx13. WAP to implement Singly Linked Lists.

posted Mar 12, 2011, 7:32 AM by Neil Mathew   [ updated Mar 12, 2011, 7:37 AM ]

SOURCE CODE:

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#include<stdio.h>
 
int count; // Total number of nodes in Singly Linked List.
 
struct node
{
       int info;
       struct node * next;
}*start,*ptr;
 
int INS(int ITEM, int pos)
{
    
     struct node * newnode;
     newnode= (struct node *) malloc ( sizeof(struct node) ) ;
     
     newnode->info=ITEM;
     newnode->next=NULL;
     
     // ERROR HANDLING #1 - No Memory Left (Overflow)
     if( newnode == NULL )
     {
      printf(" OVERFLOW: No Memory Left to create newnode. ");
      return 0;
     }
     
     // ERROR HANDLING #2 - Position Over Limits
     if( pos<=0 || pos>count+1 )
     {
      printf(" Position entered is over limits. ");
      return 0;
     }
     
     // Condition 1: First node of LL
     if( start==NULL )
     {
      start=newnode;
      count=1;
     }
     // Condition 2: Adding node to first position of LL
     else if( pos==1)
     {
      newnode->next=start;
      start=newnode;
      count++;   
     }
     // Condition 3: Adding node to any other position of LL
     else
     {    
     
      int i;
      ptr=start;
 
      for(i=2; i<=pos-1; i++)
      ptr=ptr->next;
        
      newnode->next = ptr->next;
      ptr->next = newnode;
      
      count++;
     }
        
     return 1; //successful 
}
 
int DEL(int pos)
{
    struct node *temp;
    
    //ERROR HANDLING #1 - Underflow
    if(start == NULL)
    {
     printf(" UNDERFLOW: No Node left to delete. ");
     return 0;
    }
    
    //ERROR HANDLING #2 - Position Over Limits
    if( pos<=0 || pos>count )
    {
     printf(" Position entered is over limits. ");
     return 0;
    }
    
 
    
    // Condition 1: Deleting First Node OR Last Remaining Node
    if( pos==1 )
    {
     temp=start;
     start=start->next;
     free(temp);
     count--;
    }
    // Condition 2: Deleting any other node
    else
    {
     int i;
     ptr=start;
     for(i=2; i<=pos-1; i++)
     ptr=ptr->next;
    
     temp=ptr->next;
     ptr->next=temp->next;
     free(temp);
     
     count--;
    }    
    
    return 1;
}
    
 
int TRAVERSE()
{  
 
   ptr=start;
   
   // ERROR HANDLING
   if(start==NULL)
   {
    printf(" Linked List Empty. No Nodes to display. ");
    return 0;
   }
 
   // TRAVERSING 
   int i;
   printf("\n [");
   for(i=1; i<=count; i++, ptr=ptr->next) 
   { 
    printf(" - %d",ptr->info); 
   }
   printf(" - ]");
   
   return 1;
} 
 
 
int main()
{
    int item,pos=1;
    int ch,success;
    start=NULL;
    count=0;
        
    do
    {
    printf("\n\n MENU:");
    printf("\n 1. Insert a node. ");
    printf("\n 2. Delete a node. ");
    printf("\n 3. Display the Singly Linked List. ");
    printf("\n 4. EXIT. \n Your Choice: ");
    scanf("%d",&ch);
    
    switch(ch)
    {
    case 1: //INSERT
        
    printf("\n ENTER ITEM: ");
    scanf("%d", &item);
    
    if(start!=NULL)
    { 
     printf("\n ENTER POSITION: ");
     scanf("%d", &pos);
    }
    
    success=INS(item,pos);
    break;
    
    case 2: //DELETE
    
    if(start!=NULL)
    { 
     printf("\n ENTER POSITION: ");
     scanf("%d", &pos);
    }
    
    success=DEL(pos);
    break;
    
    case 3: //DISPLAY
    printf("\n The Nodes: \n");
    success=TRAVERSE();
    break;
    
    case 4: 
    printf("\n Exiting.. ");
    break;
    
    default: printf(" INVALID CHOICE. ");
    }
    
    }
    while(ch!=4); //end of do while loop
    
    return 0;
}
 

OUTPUT:



 MENU:
 1. Insert a node.
 2. Delete a node.
 3. Display the Singly Linked List.
 4. EXIT.
 Your Choice: 1

 ENTER ITEM: 34


 MENU:
 1. Insert a node.
 2. Delete a node.
 3. Display the Singly Linked List.
 4. EXIT.
 Your Choice: 1

 ENTER ITEM: 56

 ENTER POSITION: 2


 MENU:
 1. Insert a node.
 2. Delete a node.
 3. Display the Singly Linked List.
 4. EXIT.
 Your Choice: 1

 ENTER ITEM: 67

 ENTER POSITION: 3


 MENU:
 1. Insert a node.
 2. Delete a node.
 3. Display the Singly Linked List.
 4. EXIT.
 Your Choice: 3

 The Nodes:

 [ - 34 - 56 - 67 - ]

 MENU:
 1. Insert a node.
 2. Delete a node.
 3. Display the Singly Linked List.
 4. EXIT.
 Your Choice: 1

 ENTER ITEM: 12

 ENTER POSITION: 1


 MENU:
 1. Insert a node.
 2. Delete a node.
 3. Display the Singly Linked List.
 4. EXIT.
 Your Choice: 3

 The Nodes:

 [ - 12 - 34 - 56 - 67 - ]

 MENU:
 1. Insert a node.
 2. Delete a node.
 3. Display the Singly Linked List.
 4. EXIT.
 Your Choice: 1

 ENTER ITEM: 0

 ENTER POSITION: 6

 Position entered is over limits.

 MENU:
 1. Insert a node.
 2. Delete a node.
 3. Display the Singly Linked List.
 4. EXIT.
 Your Choice: 2

 ENTER POSITION: 3


 MENU:
 1. Insert a node.
 2. Delete a node.
 3. Display the Singly Linked List.
 4. EXIT.
 Your Choice: 3

 The Nodes:

 [ - 12 - 34 - 67 - ]

 MENU:
 1. Insert a node.
 2. Delete a node.
 3. Display the Singly Linked List.
 4. EXIT.
 Your Choice: 4

 Exiting.. 


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