Inorder traversal non recursive

Here we show a non recursive algorithm to implement inorder traversal of binary tree.

Algorithm 

Firstly,root node is the current node.

1.Push the current node on stack and traverse its leftmost subtree.Push visited  
nodes on stack.

2.Pop a node from stack and print it.If right child exists for this node make it as 
current node.Repeat 1

Code

void inorder(node* curr)
{
    int exists = 0;

    init(s);

    push(curr);
    while(!empty())
    {
        exists = 0;
        while(curr->left!=NULL)
        {
            curr=curr->left;
            push(curr);
        }
        while(!exists && !empty())
        {
            curr=pop();
            printf("%c",curr->data);

            if(curr->right!=NULL)
            {
                    curr = curr->right;
                    push(curr);
                    exists = 1;
            }
        }
    }
}

Exists variable is used to check whether right child of popped node exists.

Code Tracing