search binary tree

[donaldunca]

This is my code:

#include<stdio.h>
#include<conio.h>
#include<alloc.h>
#include<string.h>
#include<dos.h>
typedef struct node *nodeptr;
typedef int    infor;
struct     node
{       infor data;
    nodeptr left;
    nodeptr right;
};

void    insert(nodeptr p,nodeptr *T);
void    insert_node(infor e,nodeptr *T);

void    freenode(nodeptr p)
{    free(p);
}

void    init(nodeptr *T)
{       *T=NULL;
}

nodeptr    remove(nodeptr p)
{    nodeptr rp,f;
    if(p==NULL)
    {    printf("Don't have p");
        return(p);
    }
    if(p->right==NULL)    rp=p->left;
    else
    {    if(p->left==NULL)
        rp=p->right;
        else
        {    f=p;
            rp=p->right;
            while(rp->left!=NULL)
            {    f=rp;
                  rp=rp->left;
            }
            if(f!=p)
            {    f->left=rp->right;
                 rp->right=p->right;
                 rp->left=p->left;
            }
            else    rp->left=p->left;
        }
    }
    free(p);
    return(rp);
}

nodeptr    search(nodeptr proot,int x)
{    nodeptr p;
    p=proot;
    if(p!=NULL)
    {    if(x<proot->data)
            p=search(proot->left,x);
        else    if(x>proot->data)
                p=search(proot->right,x);
    }
    return(p);
}

void    prerder(nodeptr proot)
{    if(proot!=NULL)
    {    printf("%3d",proot->data);
        preorder(proot->left);
        preorder(proot->right);
    }
}

void    inorder(nodeptr proot)
{    if(proot!=NULL)
    {
        inorder(proot->left);
        printf("%3d",proot->data);
        inorder(proot->right);
    }
}

void    posorder(nodeptr proot)
{    if(proot!=NULL)
    {
        posorder(proot->left);
        posorder(proot->right);
        printf("%3d",proot->data);
    }
}

void    cleartree(nodeptr proot)
{    if(proot!=NULL)
    {    cleartree(proot->left);
        cleartree(proot->right);
        freenode(proot);
    }
}
void     createtree(nodeptr *T)
{    int e;
    do
    {    printf("Enter your number (-1 to exit):");
          scanf("%d",&e);
          if(e!=-1)    insert_node(e,T);
    }while(e!=-1);
}

void    insert(nodeptr p,nodeptr *T)
{    if(p->data<(*T)->data)
        if((*T)->left)      insert(p,&(*T)->left);
            else    (*T)->left=p;
    else
        if(p->data>(*T)->data)
            if((*T)->right)      insert(p,&(*T)->right);
            else    (*T)->right=p;
}

void    insert_node(infor e,nodeptr *T)
{    nodeptr p;
    p=(nodeptr)malloc(sizeof(struct node));
    p->data=e;
    p->left=NULL;
    p->right=NULL;
    if(*T==NULL)    (*T)=p;
    else        insert(p,T);
}

main()
{    nodeptr T,p;
    int number,select;
    init(&T);
    do
    {   clrscr();
        printf("1-createtree\n");
        printf("2-preorder\n");
        printf("3-inorder\n");
        printf("4-posorder\n");
        printf("5-insert node\n");
        printf("6-search\n");
        printf("7-remove proot node\n");
        printf("8-remove left node\n");
        printf("9-remove right node\n");
        printf("10-remove all node\n");
        printf("11-exit\n");
        printf("ban chon cong viec nao:");scanf("%d",&select);
        switch(select)
        {    case 1: createtree(&T);
                break;
            case 2:
                if(T==NULL)  printf("empty tree");
                else preorder(T);
                getch();
                break;
            case 3:
                if(T==NULL)  printf("empty tree");
                else inorder(T);
                getch();
                break;
            case 4:
                if(T==NULL)  printf("empty tree");
                else posorder(T);
                getch();
                break;
            case 5: createtree(&T);
                break;
            case 6:
                printf("what number do you want to search:");scanf("%d",&number);
                if(search(T,so))
                    printf("had your number");
                else     printf("hadn't your number");
                getch();
                break;
            case 7:
                T=remove(T);
                break;
            case 8:
                printf("content of father node:");scanf("%d",&number);
                p=search(T,number);
                if(p!=NULL)    p->left=remove(p->left);
                else    printf("hadn't father node");
                break;
            case 9:
                printf("content of father node:");scanf("%d",&number);
                p=search(T,number);
                if(p!=NULL)    p->right=remove(p->right);
                else    printf("hadn't father node");
                break;
            case 10:cleartree(T);
                break;
        }
    }while(ch!=11);
    cleartree(T);
    T=NULL;
}

I have some question:
- proot don't declare in main program but the program still run true. I don't understand this problem
- insert (p,T) is true, but why not insert(p,&T)
- case 10: remove all node. It can't run
Thanks!

[Rashakil Fol]

- I don't understand the question.
- The expression (&T) returns a value of type nodeptr**, when T is of type nodeptr*, but insert expects an argument of type nodeptr*.
- Case 10 doesn't change the value of T, so the nodeptr T still points at the same place in memory as it pointed before. Technically, that memory is freed, and it could be overwritten when another block of memory is allocated and written over. However, until that happens, the values in memory are still there. Perhaps you should make cleartree a function with the declaration void cleartree(nodeptr* T) , so that it can set *T = NULL;