Here is source code of the C Program to create a mirror copy of a tree and display using BFS traversal. The C program is successfully compiled and run on a Linux system. The program output is also shown below.

/*
* C Program to Create a Mirror Copy of a Tree and Display using
* BFS Traversal
* 40
* /\
* 20 60
* /\ \
* 10 30 80
* \
* 90
*/

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

struct btnode
{
int value;
struct btnode *left, *right;
};
typedef struct btnode node;

/* function prototypes */
void insert(node *, node *);
void mirror(node *);

/* global variables */
node *root = NULL;
int val, front = 0, rear = -1, i;
int queue[20];

void main()
{
node *new = NULL ;
int num = 1;
printf("Enter the elements of the tree(enter 0 to exit)\n");
while (1)
{
scanf("%d", &num);
if (num == 0)
break;
new = malloc(sizeof(node));
new->left = new->right = NULL;
new->value = num;
if (root == NULL)
root = new;
else
{
insert(new, root);
}
}
printf("mirror image of tree is\n");
queue[++rear] = root->value;
mirror(root);
for (i = 0;i <= rear;i++)
printf("%d -> ", queue[i]);
printf("%d\n", root->right->right->right->value);
}

/* inserting nodes into the tree */
void insert(node * new , node *root)
{
if (new->value > root->value)
{
if (root->right == NULL)
root->right = new;
else
insert (new, root->right);
}
if (new->value < root->value)
{
if (root->left == NULL)
root->left = new;
else
insert (new, root->left);
}
}

/* mirror image of nodes */
void mirror(node *root)
{
val = root->value;
if ((front <= rear) && (root->value == queue[front]))
{
if (root->right != NULL || root->right == NULL)
queue[++rear] = root->right->value;
if (root->left != NULL)
queue[++rear] = root->left->value;
front++;
}
if (root->right != NULL)
{
mirror(root->right);
}
if (root->left != NULL)
{
mirror(root->left);
}
}


$ cc tree16.c
$ a.out
Enter the elements of the tree(enter 0 to exit)
40
20
10
30
60
70
80
0
mirror image of tree is
40 -> 60 -> 20 -> 70 -> 30 -> 10 -> 80