C Program to Traverse Binary Tree using Recursion

By | 28.11.2016

Traverse Binary Tree using Recursion


Write a C Program to Traverse Binary Tree using Recursion. Here’s simple Program to Traverse Binary Tree using Recursion in C Programming Language.


Recursion : :


  • Recursion is the process of repeating items in a self-similar way. In programming languages, if a program allows you to call a function inside the same function, then it is called a recursive call of the function.
  • The C programming language supports recursion, i.e., a function to call itself. But while using recursion, programmers need to be careful to define an exit condition from the function, otherwise it will go into an infinite loop.
  • Recursive functions are very useful to solve many mathematical problems, such as calculating the factorial of a number, generating Fibonacci series, etc.

Problem : :


The following C program, using recursion, performs traversal operation across the nodes in a tree. The tree we have used is the binary search tree. The user generates a tree by inserting integers. The user is also asked to select one of the three modes of traversal, ie, infix, prefix and postfix.

Here is the source code of the C Program to Traverse Binary Tree using Recursion. The C Program is successfully compiled and run on a Linux system. The program output is also shown below.


SOURCE CODE : 


/*  C Program to Traverse Binary Tree using Recursion  */

#include <stdio.h>
#include <stdlib.h>
 
struct node
{
    int a;
    struct node *left;
    struct node *right;
};
 
void generate(struct node **, int);
void infix(struct node *);
void postfix(struct node *);
void prefix(struct node *);
void delete(struct node **);
 
int main()
{
    struct node *head = NULL;
    int choice = 0, num, flag = 0, key;
 
    do
    {
        printf("\nEnter your choice:\n1. Insert\n2. Traverse via infix\n3.Traverse via prefix\n4. Traverse via postfix\n5. Exit\nChoice: ");
        scanf("%d", &choice);
        switch(choice)
        {
        case 1: 
            printf("Enter element to insert: ");
            scanf("%d", &num);
            generate(&head, num);
            break;
        case 2: 
            infix(head);
            break;
        case 3: 
            prefix(head);
            break;
        case 4: 
            postfix(head);
            break;
        case 5: 
            delete(&head);
            printf("Memory Cleared\nPROGRAM TERMINATED\n");
            break;
        default: printf("Not a valid input, try again\n");
        }
    } while (choice != 5);
    return 0;
}
 
void generate(struct node **head, int num)
{
    struct node *temp = *head, *prev = *head;
 
    if (*head == NULL)
    {
        *head = (struct node *)malloc(sizeof(struct node));
        (*head)->a = num;
        (*head)->left = (*head)->right = NULL;
    }
    else
    {
        while (temp != NULL)
        {
            if (num > temp->a)
            {
                prev = temp;
                temp = temp->right;
            }
            else
            {
                prev = temp;
                temp = temp->left;
            }
        }
        temp = (struct node *)malloc(sizeof(struct node));
        temp->a = num;
        if (num >= prev->a)
        {
            prev->right = temp;
        }
        else
        {
            prev->left = temp;
        }
    }
}
 
void infix(struct node *head)
{
    if (head)
    {
        infix(head->left);
        printf("%d   ", head->a);
        infix(head->right);
    }
}
 
void prefix(struct node *head)
{
    if (head)
    {
        printf("%d   ", head->a);
        prefix(head->left);
        prefix(head->right);
    }
}
 
void postfix(struct node *head)
{
    if (head)
    {
        postfix(head->left);
        postfix(head->right);
        printf("%d   ", head->a);
    }
}
 
void delete(struct node **head)
{
    if (*head != NULL)
    {
        if ((*head)->left)
        {
            delete(&(*head)->left);
        }
        if ((*head)->right)
        {
            delete(&(*head)->right);
        }
        free(*head);
    }
}

Output : :


Enter your choice:
1. Insert
2. Traverse via infix
3. Traverse via prefix
4. Traverse via postfix
5. Exit

Choice: 1
Enter element to insert: 5
 
Enter your choice:
1. Insert
2. Traverse via infix
3. Traverse via prefix
4. Traverse via postfix
5. Exit

Choice: 1
Enter element to insert: 3
 
Enter your choice:
1. Insert
2. Traverse via infix
3. Traverse via prefix
4. Traverse via postfix
5. Exit

Choice: 1
Enter element to insert: 4
 
Enter your choice:
1. Insert
2. Traverse via infix
3. Traverse via prefix
4. Traverse via postfix
5. Exit

Choice: 1
Enter element to insert: 6
 
Enter your choice:
1. Insert
2. Traverse via infix
3. Traverse via prefix
4. Traverse via postfix
5. Exit
Choice: 1
Enter element to insert: 2
 
Enter your choice:
1. Insert
2. Traverse via infix
3. Traverse via prefix
4. Traverse via postfix
5. Exit

Choice: 2
2   3   4   5   6  
 
Enter your choice:
1. Insert
2. Traverse via infix
3. Traverse via prefix
4. Traverse via postfix
5. Exit

Choice: 3
5   3   2   4   6   

Enter your choice:
1. Insert
2. Traverse via infix
3. Traverse via prefix
4. Traverse via postfix
5. Exit

Choice: 4
2   4   3   6   5  
 
Enter your choice:
1. Insert
2. Traverse via infix
3. Traverse via prefix
4. Traverse via postfix
5. Exit

Choice: 5

Above is the source code for C Program to Traverse Binary Tree using Recursion which is successfully compiled and run on Windows System.The Output of the program is shown above .

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About Tunde A

My name is Tunde Ajetomobi, a Tech Enthusiast and Growth Hacker. I enjoy creating helpful content that solves problem across different topics. Codezclub is my way of helping young aspiring programmers and students to hone their skills and find solutions on fundamental programming languages.

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