Here is source code of the C Program to construct a binary tree. The C program is successfully compiled and run on a Linux system. The program output is also shown below.

/*
* C Program to Construct a B Tree
*/

/***************************
* binarytree.h
***************************/

typedef char DATA;

struct node
{
DATA d;
struct node *left;
struct node *right;
};

typedef struct node NODE;
typedef NODE *BTREE;

BTREE newnode(void);
BTREE init_node(DATA d, BTREE p1, BTREE p2);
BTREE create_tree(DATA a[], int i, int size);
void preorder (BTREE root);
void inorder (BTREE root);
void postorder (BTREE root);

/**********************
* binarytree.c:
***********************/
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include "binarytree.h"

BTREE new_node()
{
return ((BTREE)malloc(sizeof(NODE)));
}

BTREE init_node(DATA d1, BTREE p1, BTREE p2)
{
BTREE t;

t = new_node();
t->d = d1;
t->left = p1;
t->right = p2;
return t;
}

/* create a linked binary tree from an array */
BTREE create_tree(DATA a[], int i, int size)
{
if (i >= size)
return NULL;
else
return(init_node(a[i],
create_tree(a, 2*i+1, size),
create_tree(a, 2*i+2, size)));
}

/* preorder traversal */
void preorder (BTREE root)
{
if (root != NULL) {
printf("%c ", root->d);
preorder(root -> left);
preorder(root -> right);
}
}

/* Inorder traversal */
void inorder (BTREE root)
{
if (root != NULL) {
inorder(root -> left);
printf("%c ", root->d);
inorder(root -> right);
}
}

/* postorder binary tree traversal */

void postorder (BTREE root)
{
if (root != NULL) {
postorder(root -> left);
postorder(root -> right);
printf("%c ", root->d);
}
}

/***************************
* pgm.c
***************************/
#include
#include
#include

#include "binarytree.c"
#define ARRAY_SIZE 10
int main(void)
{
char a[ARRAY_SIZE] = {'g','d','i','b','f','h','j','a','c','e'};
BTREE root;

root = create_tree(a, 0, ARRAY_SIZE) ;
assert(root != NULL);
printf("PREORDER\n");
preorder(root);
printf("\n");
printf("INORDER\n");
inorder(root);
printf("\n");

printf("POSTORDER\n");
postorder(root);
printf("\n");
}


$ cc pgm61.c
$ a.out
PREORDER
g d b a c f e i h j
INORDER
a b c d e f g h i j
POSTORDER
a c b e f d h j i g