Simple Binary Tree Creation and Traversal

A binary tree is a tree data structure in which each node has at most two child nodes, usually distinguished as "left" and "right". Nodes with children are parent nodes, and child nodes may contain references to their parents. Outside the tree, there is often a reference to the "root" node (the ancestor of all nodes), if it exists. Any node in the data structure can be reached by starting at root node and repeatedly following references to either the left or right child.

---

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


  struct node
      {
           int val;
           struct node *right, *left;
      };

  void insert(struct node **root, struct node *cur)
      {
           if(!(*root))
              {
                   *root = cur;
                   return;
              }
           if(cur->val<=(*root)->val)
                   insert(&(*root)->left, cur);
           else if(cur->val>(*root)->val)
                   insert(&(*root)->right, cur);
      }

  void Preorder(struct node *root)
      {
           printf("%d ",root->val);
           if(root->left)
                   Preorder(root->left);
           if(root->right)
                   Preorder(root->right);

      }

      void Inorder(struct node *root)
           {
              if(root->left)
                        Inorder(root->left);
              printf("%d ",root->val);
              if(root->right)
                        Inorder(root->right);

           }
      void Postorder(struct node *root)
           {
              if(root->left)
                        Postorder(root->left);
              if(root->right)
                   Postorder(root->right);
              printf("%d ",root->val);
           }

  int main()
      {
           int ch;
           struct node *curr, *root;
           root = NULL;
           do
              {
                   printf("\n\n\t1. Insert");
                   printf("\n\t2. Preorder");
                   printf("\n\t3. Inorder");
                   printf("\n\t4. Postorder");
                   printf("\n\t5. Exit");
                   printf("\n\tEnter a Choice : ");
                   scanf("%d",&ch);
                   switch(ch)
                        {
                            case 1:
                                curr = (struct node *)malloc(sizeof(struct node));
                                curr->left = curr->right = NULL;
                                printf("\n\tEnter a No ");
                                scanf("%d",&curr->val);
                                insert(&root, curr);
                                break;
                            case 2:
                                     printf("\n\tPreorder Traversal : ");
                                     Preorder(root);
                                     break;
                            case 3:
                                     printf("\n\tInorder Traversal : ");
                                     Inorder(root);
                                     break;
                            case 4:
                                     printf("\n\tPostrder Traversal : ");
                                     Postorder(root);
                                     break;
                            case 5:
                                     printf("\n\tQuitting ............");
                                     getch();
                                     exit(0);
                            default:
                                     printf("\n\tInvalid Option!");
                        }
              }while(ch!=5);
           getch();
      }