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Program28.c
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Program28.c
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#include <stdio.h>
#include <stdlib.h>
struct node {
int data;
struct node* next;
};
struct node* first = NULL;
struct node* createNode(int data)
{
struct node* newNode = (struct node*)malloc((sizeof(struct node)));
if(newNode == NULL)
{
printf("Sorry there was an error\n Aborting\n");
exit(0);
}
newNode->next = NULL;
newNode->data = data;
return(newNode);
}
void addElemEnd(int data)
{
struct node *newNode = createNode(data);
if(first == NULL)
{
first = newNode;
}
else
{
struct node *temp = first;
while(temp->next !=NULL)
{
temp = temp->next;
}
temp->next = newNode;
}
}
void delElemAtPos(int pos)
{
if(pos<1)
{
printf("INVALID, Index should start from 1\n");
}
else if(pos == 1)
{
if(first == NULL)
{
printf("Sorry, List Empty, cannot delete position %d",pos);
}
else
{
struct node *del = first;
first = first->next;
free(del);
printf("Element at position %d Deleted. \n",pos);
}
}
else
{
// There must be atleast pos-1 elements in the list
int elemNum = 1;
struct node *temp = first;
// on exiting temp should point to pos-1 if that pos-1 exist
// However element at pos might or might not exist, ie temp->next can be null
// or temp will be null
while(temp!=NULL && elemNum<pos-1)
{
temp = temp->next;
elemNum++;
}
// Index correction for two different kind of loop termination
// if temp == null, it means elemNum++ has run one extra time
if(temp==NULL){elemNum--;}
else {;}
if(temp == NULL || temp->next == NULL)
printf("Sorry, There are only %d nodes in the list", elemNum);
else
{
struct node *del = temp->next;
temp->next = temp->next->next;
free(del);
printf("Element Deleted at position %d. \n",pos);
}
}
}
void display()
{
if(first == NULL)
printf("\nList Empty");
else
{
struct node *temp = first;
printf("Head");
while(temp != NULL)
{
printf(" -> %d", temp->data);
temp = temp->next;
}
}
printf("\n");
}
void delete(int data)
{
if(first == NULL)
{
printf("\nList Empty");
}
else
{
struct node *temp = first, *del = NULL;
if(first->data == data)
{
del = first;
first = first->next;
free(del);
printf("\nElement Deleted! \n");
}
else
{
while(temp != NULL)
{
if(temp->next!=NULL && temp->next->data == data)
{
del = temp->next;
temp->next = temp->next->next;
free(del);
printf("\nElement Deleted! \n");
break;
}
temp = temp->next;
}
}
if(del == NULL)
printf("\nElement not found! \n");
}
}
int main()
{
int choice;
do
{
int data, pos;
printf("\n");
printf("1: Add element at end\n");
printf("2: Delete element at a given position\n");
printf("3: Display Elements\n");
printf("4: Delete Element\n");
printf("5: Exit\n");
printf("Enter your choice: ");
scanf("%d",&choice);
switch(choice)
{
case 1:
printf("Enter value: ");
scanf("%d",&data);
addElemEnd(data);
break;
case 2:
printf("Enter position at which you want to delete the value: ");
scanf("%d",&pos);
delElemAtPos(pos);
break;
case 3:
display();
break;
case 4:
printf("[First occurence will be deleted]\n");
printf("Enter value that you want to delete: ");
scanf("%d",&data);
delete(data);
break;
case 5:
break;
default:
printf("Invalid Choice\n");
break;
};
}while(choice != 5);
return 0;
}