linklist

#include<stdio.h>
#include<stdlib.h>
typedef struct data
{
    int a;
    char ch;
    struct data *next;
} data;
data *head;


void insert_at_first(int an,char chn)
{
    data *n=(data*)malloc(sizeof(data));
    n->a=an;
    n->ch=chn;
    n->next=NULL;
    if(head==NULL)
    {
        head=n;
        n->next=NULL;
    }
    else
    {
        n->next=head;
        head=n;
    }


}
void insert_at_last(int an,char chn)
{
    data *n=(data*)malloc(sizeof(data));
    n->a=an;
    n->ch=chn;
    n->next=NULL;
    data *list=head;
    while(list->next!=NULL)
    {
        list=list->next;

    }
    list->next=n;
}
void insert_at_nth()
{
    data *n=(data*)malloc(sizeof(data));
    scanf("%d",&n);
    data *list=head;
    if(head==NULL)
    {
        head=n;
        n->next=NULL;

    }
    else if(n==1)
    {
        n->next=head;
        head=n;
    }
    else
    {
        n=n-2;
        while (n!=0 && list->next!=NULL )
        {
            list=list->next;
            n--;
        }
        n->next=list->next;
        list->next=n;
    }
}


void display()
{
    data *list=head;
    while (list!=NULL)

    {
        printf("A: %d\n",list->a);

        printf("ch: %d\n",list->ch);
        list=list->next;
    }
}

void search()
{
    int n;
    data *list=head;
    scanf("%d",&n);
    while(list!=NULL)
    {
        if(list->a==n)
            return 1;

        else
            list=list->next;
    }
}


void delete_by_pos()

{
    int n;
    data *temp;
    data *list=head;
    scanf("%d",&n);

    if(head==NULL)
    {
        printf("no data found\n");
    }
    else if(n==1)
    {
        list=head;
        head=list->next;
        free(list);
    }
    else
    {
        n=n-2;
        while(n!=0)
        {
            list=list->next;
        }
        temp=list->next;
        list->next=temp->next;
        free(temp);

    }
}
void delete_by_value()
{
    int n;
    data *temp;
    data *list=head;
    scanf("%d",&n);
    if(head==NULL)
    {
        printf("no data found\n");
    }
    else if(list->a==n)
    {
        temp=head;
        head=temp->next;
        free(temp);
    }
    else
    {
        while(list->next->a!=n)
        {
            list=list->next;
        }
        temp=list->next;
        list->next=temp->next;
        free(temp);

    }
}
int main ()
{
    head=NULL;
    insert_at_first(5,'x');
    insert_at_first(6,'y');
    insert_at_first(7,'z');
    display();
    search();
    return 0;
}