# Problem with inserting nodes on Binary trees

Discussion in 'C Programming' started by Blondeamon, Dec 24, 2007.

1. ### BlondeamonGuest

Ok i'll try to be brief. As part of one of my essays i thought of
creating source code for implementation of a binary tree and its basic
functions.

My code is both from books,lecture notes and googling but for some
reason on the printing of the nodes using inOrder traversal only 2 or 3
nodes are being printed.

I will put my code here although i am sure that only few might actually
comprehend what it is about because this subject needs good knowledge of
all the tricks about inserting/deleting nodes from theory of Binary Trees.

Exercise: Create code for a binary tree.The program reads the size of
the tree N and then inserts N nodes with values between 1 and 30.000
into the tree.
You cant enter a node if it is not already on the tree,so you must
search if it exists before entering it.

Finally ,after having inserted all N nodes print them using InOrder
traversal.

Tips: My code works for the first 2 nodes...but doesnt
print anything else.And i will bust my head open if i wont figure out why.

I appreciate any help guys , this is a tough question and this is my
first time on this forum.
(seems very warm so far btw)

Code (Text):
#include <iostream>
#include <cstdlib>
#include <ctime>

using namespace std;

//the struct which represents the node
struct tnode {
struct tnode *left, *right;
int key;
};

void InOrder( tnode *x )
{
if (x == 0) return;
InOrder(x->left);
cout << x->key << " ";
InOrder(x->right);
}

int main ()
{
srand((long)2004126);
tnode *root = 0;
int size, key2;
int flag;

cout << "\nPlease enter the size of the tree.  N: ";
cin >> size;

for (int i = 0; i < size; i++) {
key2 = 1 + rand() % 30000;  //creating random node key
between 1-30.000
tnode *p = root;
tnode *q = 0 ;
flag = 0;

//searching existing tree for node with that value

while((p != 0)&&(flag==0)) {
q = p;
if (p->key == key2) {
flag = 1; //node with that key already
exists -cant enter
} else if (p->key < key2) {
p = p->left; //case 1: key smaller than root
} else {
p = p->right; //case 2: key bigger than root
}
}

//creating new node with key2 as content
if (flag == 0) { //flag is 0 when that value didnt
tnode *z = new tnode;
z->key = key2;
z->left = 0;
z->right = 0;    //creation of nw node that will
take key2 as its value
//and will have 2 NULL kids (left and right)

if (q == 0) {
root = z;
//case of empty tree
//case handling about where the new node will be put
} else if (key2 > q->key) {
q->right = z;
} else {
q->left = z;
}
}
}

//cout << "\nroot is : "<< root->key;          //not needed
,just for checking

//the value of root
InOrder(root);
cout << endl;
cin >> size;
return 0;
}

Blondeamon, Dec 24, 2007

2. ### Nikos ChantziarasGuest

Blondeamon wrote:
> [...]
> Tips:

This isn't a web forum, so I don't think BBcode is supposed to work here.

>
Code (Text):
#include <iostream>
> #include <cstdlib>
> #include <ctime>
>
> using namespace std;[/color]

It looks like C++ to me so I guess it's off-topic here.

Nikos Chantziaras, Dec 24, 2007