Program to reverse a singly linked list using C language

Program to reverse  a singly linked list

 A singly linked list is a type of list in which there  is a  pointer which point the  next node in the list.
There is a head pointer which tell that the  starting point of the list is fixed

functions used are:

User defined functions are:-
a. create();
b.display();
c.reverse();

 Library functions-:

a,getch();
b.clrscr();
c.printf();
d.scanf();




//header files are include d
#include<stdio.h>
#include<conio.h>

//creation of structure 

typedef struct list
  {
    int data;
    struct list *next;
  }node;

node *start=NULL;
node *creat(node*);
node *display(node*);
node *reverse(node*);

//start of program
 void main()
   {

     int option,c=0;
     clrscr();
     do
       {
     printf("\n Main Menu");
     printf("\n1:Creat list");
     printf("\n2:Display list");
     printf("\n3:reverse");
     printf("\n0:Exit\n");
     printf("\nEnter your option:-");
     scanf("%d",&option);
        

              

     switch(option)
       {
         case 1:start=creat(start);
         printf("\nlinked list created");
         break;
         case 2:start=display(start);
         break;
         case 3:start=reverse(start);
         printf("linked list reversed");
         break;
         case 0:
         exit(0);
       }
       }

   while(option!=0);
   getch();
 }


node *creat(node *start)
  {
    node *ptr,*newnode;
    int num;
    printf("Enter data,pres 999 to exit:-");
    scanf("%d",&num);
    while(num!=999)
      {
     newnode=(node*)malloc(sizeof(node));
     newnode->data=num;
     if(start==NULL)
       {
         newnode->next=NULL;
         start=newnode;
       }
     else
       {
         ptr=start;
         while(ptr->next!=NULL)
         ptr=ptr->next;
         ptr->next=newnode;
         newnode->next=NULL;
       }
         printf("Enter another data:-");
         scanf("%d",&num);
       }
     return start;
      }

  node*  display(node* start)
  {
  node *ptr;
  ptr=start;
  while(ptr!=NULL)
  {
  printf("\%d->",ptr->data);
  ptr=ptr->next;
  }
  return start;
  }


node *reverse(node* start)

   {
    node *ptr,*preptr;
      node *next;
      ptr=start;
      {
      while(ptr!=NULL)
       {
       next=ptr->next;
       ptr->next=preptr;
       preptr=ptr;
       ptr=next;
       }
     start=preptr;
    }

    return(start);
   }

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