DS Lab 4- Position Linked List

#include <stdio.h>
#include <stdlib.h>

struct node{
    int data;
    struct node *next;
}*head;

void add(int num)
{
    struct node *temp;
    temp=(struct node*)malloc(sizeof(struct node));

    temp->data=num;

    if(head==NULL){
        head=temp;
        temp->next=NULL;
    }
    else{
        temp->next=head;
        head=temp;
    }
}

void append(int num)
{
    struct node *temp, *right;

    temp=(struct node*)malloc(sizeof(struct node));
    temp->data=num;
    right=(struct node*)head;

    while(right->next!=NULL)
        right=right->next;
        right->next=temp;
        right=temp;
        right->next=NULL;
}

void add_after(int num, int loc)
{
    int i;
    struct node *temp,*left,*right;
    right=head;
    for(i=1;i<loc;i++){
        left=right;
        right=right->next;
    }

    temp=(struct node*)malloc(sizeof(struct node));
    temp->data=num;
    left->next=temp;
    left=temp;
    left->next=right;
}


int count(){
    struct node *temp;
    int count=0;
    temp=head;
        while(temp!=NULL){
            count++;
            temp=temp->next;
        }
        return count;
}


void insert(int num){
    int c=0;
    struct node *temp;
    temp=head;
    if(temp==NULL){
        add(num);
    }
    else{
        while(temp!=NULL){
            if(temp->data<num)
                c++;
                temp=temp->next;
        }
        if(c==0){
            add(num);
        }
        else if(c<count()){
            add_after(num,++c);
        }
        else{
            append(num);
        }
    }
}

struct node *positionNode(int index , int x){

if(index < 0){
    return NULL;
}

int currIndex = 1;

struct node *currNode = head ;

while(currNode!=NULL && index > currIndex){

    currNode = currNode->next;

    currIndex++;
}


if(index > 0 && currNode==NULL){
    return NULL;
}


node *newNode = (struct node *)malloc(sizeof(struct node));
newNode->data = x;


if(index==0){
    newNode->next = head;
    head = newNode ;
}
else{
    newNode->next = currNode->next;
    currNode->next = newNode ;
}

return newNode ;
}

void Display(){
    struct node *temp;
    temp=head;
    if(temp==NULL)
        printf("List is empty\n\n");
    else{
        while(temp!=NULL){
            printf("%d ",temp->data);
            temp=temp->next;
        }
        printf("\n\n");
    }
}

int del (int num)
{
    struct node *temp,*prev;
    temp=head;
    while(temp!=NULL){
        if(temp->data==num){
            if(temp==head){
                head=temp->next;
                free(temp);
                return 1;
            }
            else{
                prev->next=temp->next;
                free(temp);
                return 1;
            }
        }
        else{
            prev=temp;
            temp=temp->next;
        }
    }
    return 0;
}

void positionDelete(int index)
{
    struct node *temp,*prev;
    int i=1;
    temp=head;

    if(index>count())
        printf("Invalid\n");
    else{
        while(1){
        if(i==index){
            if(temp==head){
                head=temp->next;
                free(temp);
                printf("Delete Succesfully\n");
                break;
            }
            else{
                prev->next=temp->next;
                free(temp);
                printf("Delete Succesfully\n");
                break;
            }
        }
        else{
            i++;
            prev=temp;
            temp=temp->next;
        }
        }
    }
}

int main()
{
    int num,n,op,ch,pos,x,chs,index;
    while(1){
        printf("Press 1 for Insert\nPress 2 for Display\nPress 3 for Size\nPress 4 for delete\nPress 5 for exit\n\n");

        scanf("%d", &op);
        if(op==1){
            printf("1 for normal insert\n2 for Position insert\n");
            scanf("%d",&ch);
            if(ch==1){
                printf("Enter Number: ");
                scanf("%d",&num);
                insert(num);
            }
            else if(ch==2){
                printf("Enter Position : ");
                scanf("%d", &pos);
                printf("Enter Number: ");
                scanf("%d", &x);
                positionNode(pos-1,x);
            }
            else
                printf("Invalid\n\n");
        }

        else if(op==2){
            Display();
        }
        else if(op==3)
            printf("Size is %d\n", count());
        else if(op==4){
            printf("Press 1 for num delete\nPress 2 for position delete\n");
            scanf("%d",&chs);
            if(chs==1){
                printf("Enter num for delete : ");
                scanf("%d", &n);
                if(del(n)==1)
                    printf("%d is deleted succesfully\n",n);
                else
                    printf("%d is not found\n");
            }
            else if(chs==2){
                printf("Enter the position : ");
                scanf("%d", &index);
                positionDelete(index);
            }

            else
                printf("Invalid Option\n\n");
            }
        else
            break;
    }

    return 0;
}