expression_tree.h

class ETNode {
public:
    char value;
    ETNode *left, *right;
    ETNode(char value_);
    ETNode(char value_, ETNode* left_, ETNode* right_);
};

// A very simple expression tree class that converts a parenthesized input
// consisting of addition and multiplication operations, into an expression tree.
// Traversal of this expression tree generates various Polish notations.

class Expression_Tree {
public:
	Expression_Tree() { root = 0; };
	~Expression_Tree() { clear(root); }
	void build_expression_tree(char[], int);
	void inorder() { inorder(root); }
	void preorder() { preorder(root); }
	void postorder() {postorder(root); }
private:
	ETNode* root;
	void visit(ETNode*);
	void inorder(ETNode*);
	void preorder(ETNode*);
	void postorder(ETNode*);
	void clear(ETNode*);
};