Tree traversal

i'm trying to implement a pre order tree traversal on a name however i get an error "name undeclared in funtion pre order"

what have i done wrong? how do i fix it? will my code perform what i want it to? any help is appreciated;

Code:

---


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

typedef struct tree
{
    char name[20];
    struct tree *left;
    struct tree *right;
}Tree;   

Tree *makenode( char *in, Tree *l, Tree *r)
{
    Tree *t=malloc(sizeof(Tree));
    t->left =l;
    t->right =r;
    strncpy(t->name,in,19);
    return t;
}   

Tree *insert( Tree *root, char *what)
{
    if(root==NULL)
    {root=makenode(what,NULL,NULL);}
    else if(strcmp(what, root->name)<0)
    {root->left =insert(root->left,what);}
    else{root->right =insert(root->right,what);
}
return root;
}   

char *preorder(Tree *root, char *what)
{
        if(root==NULL)
                {return "NOT FOUND";}
        printf("%s ",root->name);
        preorder(root->left,name);
        preorder(root->right,name);
}

int main(void)
{
    char s[20];
    Tree *tree =NULL;
    do{
        scanf("%s",s);
        if(strcmp(s,".")==0)
        {break;}
        if(strcmp(s,".")!=0);
        {tree=insert(tree,s);}
    }
    while(strcmp(s,".")!=0);
    preorder(tree,s);
return 0;
}

---

thanks

>what have i done wrong?
Just what the error says you've done wrong. You're using name, but name doesn't exist:

Code:

---

char *preorder(Tree *root, char *what)
{
        if(root==NULL)
                {return "NOT FOUND";}
        printf("%s ",root->name);
        preorder(root->left,name);
        preorder(root->right,name);
}

---

It looks more like you want a binary search rather than a preorder traversal:

Code:

---

char *search(Tree *root, char *what)
{
  if (root == NULL)
    return "NOT FOUND";
  else if (strcmp(what, root->name) < 0)
    return search(root->left, what);
  else if (strcmp(what, root->name) > 0)
    return search(root->right, what);
  else
    return root->name;
}

---

ok looks like ive messed up badly , all i want to do is perform pre order tree traversal, e.g. go left, right , root , how do i do this?

>how do i do this?

Code:

---

void preorder(Tree *root)
{
  if (root == NULL)
    return;

  printf("%s\n", root->name);
  preorder(root->left);
  preorder(root->right);
}

---

thanks prelude