trees- no output

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

struct tree
{
    int info;
    struct tree *left;
    struct tree *right;
    struct tree *baap;
};

typedef struct tree *ptr;
ptr root= NULL;
ptr present=NULL;

ptr maketree()
{
    ptr p;
    p=(ptr)malloc(sizeof(struct tree));
    if(p==NULL)
    {
        printf("cannot create\n");
        return NULL;
    }
    else
        return p;
}

void addleft(ptr q)
{
    ptr p=NULL;
    p=maketree();
    printf("enter data:\n");
    scanf("%d",&p->info);
    p->left=NULL;
    p->right=NULL;
    q->left=p;
    p->baap=q;
}

void addright(ptr q)
{
    ptr p;
    p=maketree();
    printf("enter data:\n");
    scanf("%d",&p->info);
    p->left=NULL;
    p->right=NULL;
    q->right=p;
    p->baap=q;
}

void display(ptr abc)
{
    if(abc!=NULL)
    {
        printf("%d ",abc->info);

        display(abc->left);
        display(abc->right);
    }

}



void main()
{
    int a;
    printf("enter choice:\n");
    printf("0 to exit\n");
    printf("1.start tree (root)\n");
    printf("2.make left leaf\n");
    printf("3.make right leaf\n");
    printf("4.goto parent\n");
    printf("5.goto left\n");
    printf("6.goto right\n");
    printf("7.display tree\n");
    scanf("%d",&a);
    do
    {
    switch(a)
    {
    case 0:
        break;

    case 1:
        if(root==NULL)
        {
            root=maketree();
            printf("enter data\n");
            scanf("%d",&root->info);
            present=root;
        }
        else
            printf("root already exists\n");
        break;

    case 2:
        if(present->left!=NULL)
            addleft(present);
        else
            printf("data already exists in this location\n");
        break;

    case 3:
        if(present->right!=NULL)
            addright(present);
        else
            printf("data already exists in this location\n");
        break;

    case 4:
        if(present->baap!=NULL)
            present=present->baap;
        else
            printf("present position is root\n");
        break;

    case 5:
        if(present->left!=NULL)
            present=present->left;
        else
            printf("present position is a leaf\n");
        break;

    case 6:
        if(present->right!=NULL)
            present=present->right;
        else
            printf("present position is a leaf\n");
        break;

    case 7:
        display(root);
        break;

    default:
        printf("invalid operation");
        break;
    }
    printf("enter choice:\n");
    scanf("%d",&a);
    }while(a!=0);
}