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

/*
* C Program to Traverse the Tree Recursively
*/
#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);
}
}