Singly Linked List

//Singly linked list

#include <stdio.h>
#include <iostream>
using namespace std;

struct ListNode{
    int data;
    struct ListNode *next;
};

int ListLength(struct ListNode *head){
    int count=0;
    struct ListNode *curr=head;
    while(curr!=NULL){
        printf("%d", curr->data);
        curr = curr->next;
        count++;
    }
    return count;    
}

//head itself is a pointer
void InsertInLinkedList(struct ListNode **ptrtohead, int data, int position){
    //preparing new node
    struct ListNode *newnode = (ListNode *)malloc(sizeof(ListNode));
    newnode->data = data;
    
    struct ListNode *head, *curr, *prevcurr;
    head=*ptrtohead;
    curr=head;
    int count=1;
    bool inserted = 0;
    
    //insert at start
    if(position==1){       
       newnode->next= head;
       *ptrtohead = newnode;
    }
    else { 
        //insert in between
        while(curr!=NULL && inserted==0){
            if(position-count==1){
                newnode->next = curr->next;
                curr->next = newnode;   
                inserted=1;
            }
            else{
                count++;
                prevcurr=curr;
                curr=curr->next;
            }
        }
        //insert at end
        if(inserted==0){
            if(position==count)
            prevcurr->next = newnode;
            else 
            printf("\nPosition too far.No insertion possible.");
        }
    }    
}

void DeleteNodefromLinkedList(struct ListNode **ptrtohead, int position){
    struct ListNode *head,*curr,*prevcurr,*del,*prevprevcurr;
    head = *ptrtohead;
    curr=head;
    int deleted=0,count=1;
    
    if(head==NULL){
        printf("List empty");
        return;
    }
    
    //delete start
    if(position==1){
        *ptrtohead = head->next;
        free(head);
    }
    else{
        //delete from in between
        while(curr!=NULL && deleted==0){
            if(position-count==1){
                del=curr->next;
                curr->next = del->next;
                free(del);
                deleted=1;
            }
            else{
                count++;
                prevprevcurr=prevcurr;
                prevcurr=curr;
                curr=curr->next;
            }
        }
            //delete at end
        if(deleted==0){
            prevprevcurr->next = NULL;
            free(prevcurr);
        }
    }   
}

void DeleteLinkedList(struct ListNode **ptrtohead){
    struct ListNode *curr,*del;
    curr = *ptrtohead;
    while(curr!=NULL){
        del=curr;
        curr=curr->next;
        free(del);
    }
    *ptrtohead = NULL;    
}

int main() {
    //creating a singly linked list
	struct ListNode *a,*b,*c,*head;
    a = (ListNode *)malloc(sizeof(ListNode));
    b = (ListNode *)malloc(sizeof(ListNode));
    c = (ListNode *)malloc(sizeof(ListNode));
    a->next = b;
    b->next = c;
    a->data = 1;
    b->data = 2;
    c->data =4;
    head=a;
    
    InsertInLinkedList(&head,5,4);
    DeleteNodefromLinkedList(&head,2);
    DeleteLinkedList(&head);
    int count = ListLength(head);
    printf("\nCount:%d", count); 
    
	return 0;
}