singly Ovi

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

typedef struct data
{
    int a;
    struct data *next;
} data;

data *head=NULL;

void insert_at_first(int x)
{
    data *new_node=(data*)malloc(sizeof(data));

    new_node->a=x;
    new_node->next=NULL;

    if(head==NULL)
    {
        head=new_node;
        return;
    }

    new_node->next=head;
    head=new_node;
}

void insert_at_end(int x)
{
    data *new_node=(data*)malloc(sizeof(data));

    new_node->a=x;
    new_node->next=NULL;

    data *temp=head;
    if(head==NULL)
    {
        head=new_node;
        return;
    }
    while(temp->next!=NULL)
    {
        temp=temp->next;
    }
    temp->next=new_node;

}
void insert_at_nth_pos(int n,int x)
{
    data *new_node=(data*)malloc(sizeof(data));
    new_node->a=x;
    new_node->next=NULL;

    if(n==1 || head==NULL)
    {
        if(head==NULL)
        {

            printf("!!! Caution:Given Position is not avavilable .\nThat's why your input was placed at the 1st Position\n\n");
        }
        new_node->next=head;
        head=new_node;
        return;
    }
    data *temp=head;
    n=n-2;
    while(n-- && temp->next!=NULL)
    {
        temp=temp->next;
    }
    new_node->next=temp->next;
    temp->next=new_node;
}
void delete_by_pos(int n)
{

    data *del=NULL;
    data *temp=head;
    if(head==NULL)
    {
        printf("\nSorry, nothing to delete\n\n");
        return;
    }
    if(n==1)
    {
        del=head;
        head=head->next;
        free(del);
    }

    n=n-2;

    while(n-- && temp->next!=NULL)
    {
        temp=temp->next;
        if(temp->next==NULL)
        {
            return;
        }
    }
    if(temp->next==NULL)
    {
        printf("\nSorry, nothing to delete\n\n");
        return;
    }
    del=temp->next;
    temp->next=del->next;
    free(del);

}
void delete_by_value(int x)
{

    data *del=NULL;
    data *temp=head;
    if(head==NULL)
    {
        printf("\nSorry, nothing to delete\n\n");
        return;
    }
    if(head->a==x)
    {
        del=head;
        head=del->next;
        free(del);
        return;
    }
    while(temp->next->a!=x)
    {
        temp=temp->next;
        if(temp->next==NULL)
        {
            printf("\nSorry, nothing to delete\n\n");
            return;
        }
    }
    del=temp->next;
    temp->next=del->next;
    free(del);
}
int sum()
{
    int s=0;
    data *temp=head;
    while(temp!=NULL)
    {
        s+=temp->a;
        temp=temp->next;

    }
    return s;
}
double avrg()
{
    double av=0;
    int count=0;
    data *temp=head;
    while(temp!=NULL)
    {
        av+=temp->a;
        count++;
        temp=temp->next;

    }
    if(count==0)
    {
        printf("\nYou have not input any value yet.\n");
        printf("***Please Chose Another option...***\n");
        return 0;
    }
    return av;
}


void print()
{

    data *temp=head;

    while(temp!=NULL)
    {
        printf("%d ",temp->a);
        temp=temp->next;
    }
    printf("\n");

}

int main()
{
    insert_at_first(33);
    insert_at_end(44);

    insert_at_nth_pos(2,45);
    print();
    delete_by_pos(2);
    delete_by_value(44);
    print();
}