traversal.c

#include <iostream> 
#include <queue> 

using namespace std;

struct node 
{ 
    int data; 
    struct node* left; 
    struct node* right; 
}; 

typedef struct node* nodeptr;

void display_preorder(nodeptr root) 
{ 
    if(!root) return; 
    cout << root->data << " "; 
    display_preorder(root->left); 
    display_preorder(root->right); 
} 

void display_inorder(nodeptr root) 
{ 
    if(!root) return; 
    display_inorder(root->left); 
    cout << root->data << " "; 
    display_inorder(root->right); 
} 

void display_postorder(nodeptr root) 
{ 
    if(!root) return; 
    display_postorder(root->left); 
    display_postorder(root->right); 
    cout << root->data << " "; 
} 

void display_levelorder(nodeptr root) 
{ 
    if(!root) return; 

    queue<nodeptr> myq; 
    myq.push(root); 

    while(!myq.empty()) 
    { 
        nodeptr tmp = myq.front(); 
        myq.pop(); 
        cout << tmp->data << " "; 
        if(tmp->left) myq.push(tmp->left); 
        if(tmp->right) myq.push(tmp->right); 
    } 
    cout << endl; 
} 

int main() 
{ 
    node g = {7, NULL, NULL};
    node f = {5, NULL, NULL};
    node e = {3, NULL, NULL};
    node d = {1, NULL, NULL};
    node c = {6, &f, &g}; 
    node b = {2, &d, &e}; 
    node a = {4, &b, &c}; 

    cout << "pre order   :: "; display_preorder(&a);  cout << endl;
    cout << "in order    :: "; display_inorder(&a);   cout << endl;
    cout << "post order  :: "; display_postorder(&a); cout << endl;
    cout << "level order :: "; display_levelorder(&a); 

        return 0; 
}

//pre order   :: 4 2 1 3 6 5 7
//in order    :: 1 2 3 4 5 6 7
//post order  :: 1 3 2 5 7 6 4
//level order :: 4 2 6 1 3 5 7