Various traversal of Binary Trees

Binary trees can be traversed by three simple methods. That are:
1) In-order
2) Pre-order
3) Post- order

More on tree traversal

To traverse a non-empty binary tree in inorder (symmetric), perform the following operations recursively at each node:

1. Traverse the left subtree.
2. Visit the root.
3. Traverse the right subtree.

To traverse a non-empty binary tree in preorder, perform the following operations recursively at each node, starting with the root node:

1. Visit the root.
2. Traverse the left subtree.
3. Traverse the right subtree.

To traverse a non-empty binary tree in postorder, perform the following operations recursively at each node:

1. Traverse the left subtree.
2. Traverse the right subtree.
3. Visit the root.

C program below illustrates three of the traversal carefully :-

struct node {

    struct node *left;

    int data;

    struct node *right;

};

void insert(struct node **p, int n) {

    if(*p == NULL) {

        *p = (struct node*) malloc(sizeof(struct node));

        (*p)->left = NULL;

        (*p)->data = n;

        (*p)->right = NULL;

    }

    else {

        if(n < (*p)->data)

            insert(&((*p)->left), n);

        else

            insert(&((*p)->right), n);

    }

}

void inorder(struct node* p) {

    if(p != NULL) {

        inorder(p->left);

        printf("%d ",p->data);

        inorder(p->right);

    }

}

void preorder(struct node* p) {

    if(p != NULL) {

        printf("%d ",p->data);

        preorder(p->left);

        preorder(p->right);

    }

}

void postorder(struct node* p) {

    if(p != NULL) {

        postorder(p->left);

        postorder(p->right);

        printf("%d ",p->data);

    }

}

int main() {

    struct node *bt = NULL;

    int t,n,i=0;

    scanf("%d",&t);

    while(t--) {

        scanf("%d",&n);

        insert(&bt, n);

        //Address to the pointer is passed to

        //retain the value of root node.

    }

    printf("In-order is:\n");

    inorder(bt);

    printf("\nPre-order is:\n");

    preorder(bt);

    printf("\nPost-order is:\n");

    postorder(bt);

    return 0;

}