All in ONE (Singly)

#include<stdio.h>
#include<stdlib.h>
menu();
add();
insert_at_first();
insert_at_last();
insert_at_nth();
Delete();
delete_by_pos();
delete_by_value();
search();
search_by_pos();
search_by_value();
display();

typedef struct node
{
    int a;
    char ch[30];
    struct node *next;
}node;

node *head=NULL, *list=NULL;

int insert_at_first()
{
    node *N=(node*)malloc(sizeof(node));
    printf("Name: \n");
    scanf(" %[^\n]", N->ch);
    printf("Roll: \n");
    printf(" %d\n", &N->a);
    if(head=NULL)
    {
        head=N;
        N->next=NULL;
    }
    else
    {
        N->next=head;
        head=N;
    }
    printf("\n1. Add\n");
    printf("2. Menu\n");
    printf("3. Exit\n");
    printf("Choose an option.\n");
    int b;
    scanf("%d", &b);
    switch(b)
    {
    case 1:
        {
        add();
        break;
        }
    case 2:
        {
        menu();
        break;
        }
    case 3:
        {
            exit(0);
            break;
        }

    default:
        {
            printf("You've chosen a wrong option!! Choose the correct one:\n");
            menu();
        }
    }
}

int insert_at_last()
    {
        node *N=(node*)malloc(sizeof(node));
    printf("Name: \n");
    scanf(" %[^\n]", N->ch);
    printf("Roll: \n");
    printf(" %d\n", &N->a);
    node *list=head;
    if(head==NULL)
    {
        head=N;
        N->next=NULL;
    }
    else
    {
        while(list->next!=NULL)
        {
            list=list->next;
        }
        N->next=list->next;
        list->next=N;
    }
    printf("\n1. Add\n");
    printf("2. Menu\n");
    printf("3. Exit\n");
    printf("Choose an option.\n");
    int c;
    scanf("%d", &c);
    switch(c)
    {
    case 1:
        {
        add();
        break;
        }
    case 2:
        {
        menu();
        break;
        }
    case 3:
        {
            exit(0);
            break;
        }

    default:
        {
            printf("You've chosen a wrong option!! Choose the correct one:\n");
            menu();
        }
    }
}

int insert_at_nth()
{
    node *N=(node*)malloc(sizeof(node));
    printf("Name: \n");
    scanf(" %[^\n]", N->ch);
    printf("Roll: \n");
    printf(" %d\n", &N->a);
    node *list=head;
    int n;
    printf("Enter the Position:\n");
    scanf("%d", &n);
    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;
    }
    printf("\n1. Add\n");
    printf("2. Menu\n");
    printf("3. Exit\n");
    printf("Choose an option.\n");
    int d;
    scanf("%d", &d);
    switch(d)
    {
    case 1:
        {
        add();
        break;
        }
    case 2:
        {
        menu();
        break;
        }
    case 3:
        {
            exit(0);
            break;
        }

    default:
        {
            printf("You've chosen a wrong option!! Choose the correct one:\n");
            menu();
        }
    }
}

int add()
{
    printf("\n1. Add at First.\n");
    printf("2. Add at Last\n");
    printf("3. Add at Nth Position\n");
    printf("4. Go to Back\n");
    int e;
    scanf("%d", &e);
     switch(e)
    {
    case 1:
        {
        insert_at_first();
        break;
        }
    case 2:
        {
        insert_at_last();
        break;
        }
    case 3:
        {
            insert_at_nth();
            break;
        }
         case 4:
        {
        menu();
        break;
        }

    default:
        {
            printf("You've chosen a wrong option!! Choose the correct one:\n");
            add();
        }
    }
}

int delete_by_pos()
{
    int n;
    printf("Enter the Position:\n");
    scanf("%d", &n);
    node *list=head, *temp;
    if(n==1)
    {
        head=list->next;
        free(list);
    }
    else
    {
        n=n-2;
        while(n!=0)
        {
            list=list->next;
            n--;
        }
        temp=list->next;
        list->next=temp->next;
        free(temp);
    }
    printf("1.\n\nMenu\n");
    printf("2.Exit\n");
    printf("Choose a Option:");
    int f;
    scanf("%d",&f);
    switch(f)
    {

    case 1:
    {
        menu();
        break;
    }
    case 2:
    {
        exit(0);
    }
    default:
    {
        printf("You've chosen a wrong option!! Choose the correct one:\n");
        menu();
        }
    }
}

int delete_by_value()
{
    int n;
    printf("Enter the value:\n");
    scanf("%d", &n);

    node *list=head;
    if(list->a==n)
    {
        head=list->next;
        free(list);
    }
    else
    {
        node *list=head, *temp;
        while(list->next->a!=n)
        {
            list=list->next;
        }
        temp=list->next;
        list->next=temp->next;
        free(temp);
    }
    printf("1.\n\nMenu\n");
    printf("2.Exit\n");
    printf("Choose a Option:");
    int g;
    scanf("%d",&g);
    switch(g)
    {

    case 1:
    {
        menu();
        break;
    }
    case 2:
    {
        exit(0);
    }
    default:
    {
        printf("You've chosen a wrong option!! Choose the correct one:\n");
        menu();
        }
    }
}

int Delete()
{
    printf("\n1. Delete by Position\n");
    printf("2. Delete by Value\n");
    printf("3. Go to Back\n");

    int h;
    scanf("%d", &h);
    switch(h)
    {
    case 1:
        {
        delete_by_pos();
        break;
        }
    case 2:
        {
        delete_by_value();
        break;
        }
    case 3:
        {
            menu();
            break;
        }

    default:
        {
            printf("You've chosen a wrong option!! Choose the correct one:\n");
            Delete();
        }
    }
}

int search_by_pos()
{
    int n;
    printf("Enter the Position:\n");
    scanf("%d", &n);
    node *list=head;
    if(n==1)
    {
        printf("\nName: %s\n", list->ch);
        printf("Roll: %d\n", &list->a);
    }
    else
    {
        n=n-2;
        while(n--)
        {
            list=list->next;
        }
        printf("\nName: %s\n", list->next->ch);
        printf("Roll: %d\n", &list->next->a);
    }
    printf("\n1. Menu\n");
    printf("2. Exit\n");
    int i;
    scanf("%d",&i);
    switch(i)
    {

    case 1:
    {
        menu();
        break;
    }
    case 2:
    {
        exit(0);
        break;
    }
    default:
        {
            printf("You've chosen a wrong option!! Choose the correct one:\n");
            menu();
        }
    }
}

int search_by_value()
{
    int n;
    printf("Enter the Value:\n");
    scanf("%d", &n);
    node *list=head;
    while(1)
    {
    if(list->a==n)
    {
        printf("\nName: %s\n", list->ch);
        printf("Roll: %d\n", &list->a);
        break;
    }
    list=list->next;
    }
     printf("\n1. Menu\n");
    printf("2. Exit\n");
    int j;
    scanf("%d",&j);
    switch(j)
    {

    case 1:
    {
        menu();
        break;
    }
    case 2:
    {
        exit(0);
        break;
    }
        default:
        {
            printf("You've chosen a wrong option!! Choose the correct one:\n");
            menu();
        }
    }
}

int search()
{
    printf("\n1. Search by Position\n");
    printf("2. Search by Value\n");
    printf("3. Go to Back\n");

    int k;
    scanf("%d", &k);
    switch(k)
    {
    case 1:
        {
        search_by_pos();
        break;
        }
    case 2:
        {
        search_by_value();
        break;
        }
    case 3:
        {
            menu();
            break;
        }

    default:
        {
            printf("You've chosen a wrong option!! Choose the correct one:\n");
            search();
        }
    }
}

int display()
{
    node*list=head;
    if(head==NULL)
    {
        printf("\nList is empty!!\n");
        printf("Add data first!!\n");
        printf("1. Menu\n");
        printf("2. Exit\n");
        printf("Choose any option:\n");
        int p;
        scanf("%d",&p);
        switch(p)
        {
            case 1:
        {
            menu();
            break;
        }
        case 2:
        {
            exit(0);
        }
        default:
        {
            printf("You've chosen a wrong option!! Choose the correct one:\n");
            display();
        }
        }
    }
    else
    {
        while(list!=NULL)
        {
            printf("\nName: %s\n",list->ch);
            printf("Roll: %d\n",list->a);
            list=list->next;
        }
        printf("\n1. Menu\n");
        printf("2. Exit\n");
        printf("Choose any option:\n");
        int p;
        scanf("%d",&p);
        switch(p)
        {
            case 1:
        {
            menu();
            break;
        }
        case 2:
        {
            exit(0);
        }
        default:
        {
            printf("You've chosen a wrong option!! Choose the correct one:\n");
            display();
        }
        }
    }
}

int menu()
{
    printf("1. Add\n");
    printf("2. Delete\n");
    printf("3. Search\n");
    printf("4. Display\n");
    printf("5. Exit\n");
    printf("Choose any option\n");
    int o;
    scanf("%d", &o);
    switch(o)
    {
    case 1:
    {
        add();
        break;
    }
    case 2:
    {
        Delete();
        break;
    }
    case 3:
    {
        search();
        break;
    }
    case 4:
    {
        display();
        break;
    }
    case 5:
    {
        exit(0);
        break;
    }
    default:
    {
        printf("CHOOSE A CORRECT OPTION\n");
        menu();
    }
    }
}

int main()
{
    printf("..........!!Singly Link list!!........\n");
    menu();
    return 0;
}