8.Write a C Program to implement traversal of a binary tree.

#include < stdio.h>
#include < stdlib.h>
 
struct btnode
{
    int value;
    struct btnode *l;
    struct btnode *r;
}*root = NULL, *temp = NULL, *t2, *t1;
  
void insert();
void delete();
void inorder(struct btnode *t);
void create();
void search(struct btnode *t);
void preorder(struct btnode *t);
void postorder(struct btnode *t);
 
 
int flag = 1;
 
void main()
{
    int ch;
 
    printf("\nOPERATIONS ---");
    printf("\n1 - Insert an element into tree\n");
    //printf("2 - Delete an element from the tree\n");
    printf("3 - Inorder Traversal\n");
    printf("4 - Preorder Traversal\n");
    printf("5 - Postorder Traversal\n");
    printf("6 - Exit\n");
    while(1)
    {
        printf("\nEnter your choice : ");
        scanf("%d", &ch);
        switch (ch)
        {
        case 1:    
            insert();
            break;
        case 2:    
            //delete();
            break;
        case 3:    
            inorder(root);
            break;
        case 4:    
            preorder(root);
            break;
        case 5:    
            postorder(root);
            break;
        case 6:    
            exit(0);
        default :     
            printf("Wrong choice, Please enter correct choice  ");
            break;    
        }
    }
}
 
/* To insert a node in the tree */
void insert()
{
    create();
    if (root == NULL) 
        root = temp;
    else    
        search(root);    
}
 
/* To create a node */
void create()
{
    int data;
 
    printf("Enter data of node to be inserted : ");
    scanf("%d", &data);
    temp = (struct btnode *)malloc(1*sizeof(struct btnode));
    temp->value = data;
    temp->l = temp->r = NULL;
}
 
/* Function to search the appropriate position to insert the new node */
void search(struct btnode *t)
{
    if ((temp->value > t->value) && (t->r != NULL))      /* value more than root node value insert at right */
        search(t->r);
    else if ((temp->value > t->value) && (t->r == NULL))
        t->r = temp;
    else if ((temp->value < t->value) && (t->l != NULL))    /* value less than root node value insert at left */
        search(t->l);
    else if ((temp->value < t->value) && (t->l == NULL))
        t->l = temp;
}
 
/* recursive function to perform inorder traversal of tree */
void inorder(struct btnode *t)
{
  if (root == NULL)
    {
        printf("No elements in a tree to display");
        return;
    }
    
    if (t->l != NULL)    
        inorder(t->l);
  
   
    printf("%d -> ", t->value);
    
    if (t->r != NULL)    
        inorder(t->r);
}
 
 
 
/* To find the preorder traversal */
void preorder(struct btnode *t)
{
    if (root == NULL)
    {
        printf("No elements in a tree to display");
        return;
    }
    
    printf("%d -> ", t->value);
    if (t->l != NULL)    
        preorder(t->l);
    if (t->r != NULL)    
        preorder(t->r);
}
 
/* To find the postorder traversal */
void postorder(struct btnode *t)
{

    if (root == NULL)
    {
        printf("No elements in a tree to display ");
        return;
    }
     
    if (t->l != NULL) 
        postorder(t->l);
    if (t->r != NULL) 
        postorder(t->r);
        
   
     printf("%d -> ", t->value);
     
   
   
}