#include "exptree.h"
 
 
void make_exptree( treenodeptr *root, char *postfix ){
    char **arr_exp;
    int  argn, i;
    expstack mystack;
    expop    myop;
    treenode *newnode;
    char space = ' ';
 
    mystack = make_stack(100);
 
    arr_exp = exptok(postfix, &argn);
 
    for(i=0; i<argn; i++){
       newnode = (treenodeptr) malloc( sizeof(treenode) );
       newnode->left = NULL;
       newnode->right = NULL;
 
       switch( arr_exp[i][0] ){
       case '/': case '*': case '+': case '-':
           newnode->operator = arr_exp[i][0];
           pop(mystack, &myop);
           newnode->right = (treenodeptr) myop.op;
           pop(mystack, &myop);
           newnode->left = (treenodeptr) myop.op;
           myop.op = (void *)newnode;
           push(mystack, myop);
           break;
 
       case '0':  case '1':  case '2':  case '3': case '4':
       case '5':  case '6':  case '7':  case '8': case '9':
           sscanf(arr_exp[i],"%d", &(newnode->operand));
           myop.op = (void *)newnode;
           push(mystack, myop);
           break;
 
       default:
           break;
       }     
    }
 
    pop(mystack, &myop);
    *root = (treenodeptr) myop.op;
    destroy_stack(mystack);
    destroy_exp(arr_exp, argn);
}
 
/*-----------------------------------------------------------*/
 
void destroy_exptree( treenodeptr * root){
    if (*root == NULL)
        return;
 
    destroy_exptree( &((*root)->left) );
    destroy_exptree( &((*root)->right) );
    free( *root );
    *root = NULL;
}
 
/*-----------------------------------------------------------*/
 
int eval_exptree( treenodeptr exp_root){
    [COLOR=DarkRed]this is the prat that i am having problem  with[/COLOR]
  --> /* implement me */ 
 
}

if (is_operand())
  return value;
 
T a = recurse(left);
T b = recurse(right);
 
switch (operator()) {
case '+': return a + b;
case '-': return a - b;
case '*': return a * b;
case '/': return a / b;
}