Expression Tree, Programming Languages

For this assignment you will read a file expression.txt and create an expression tree. The expression will be a valid infix expression with the all the necessary parentheses so that there is no ambiguity in the order of the expression. You will evaluate the expression and print the result. You will also write the prefix and postfix versions of the same expression without any parentheses.

In an expression tree the nodes are either operators or operands. The operators will be in the set [''+'', ''-'', ''*'', ''/'']. The operands will be either integers or floating point numbers. All the operand nodes will be leaves of the expression tree. All the operator nodes will have exactly two children.

The outline of your program will be as follows:

class Stack (object):

class Node (object):

class Tree (object):
def __init__ (self):

def createTree (self, expr):

def evaluate (self, aNode):

def preOrder (self, aNode):

def postOrder (self, aNode):

def main():

The function createTree() will take as input parameter an infix expression with parentheses as a String and create an Expression Tree from it. Assume that the expression string is valid.

You will take the expression string and break it into tokens. There are four different kinds of tokens - left parenthesis, right parenthesis, operator, and operand. When we read a left parenthesis we are starting a new expression and when we read a right parenthesis we are ending an expression. Here is the algorithm that you will use:

If the current token is a left parenthesis add a new node as the left child of the current node. Push current node on the stack and make current node equal to the left child.
If the current token is an operator set the current node''s data value to the operator. Push current node on the stack. Add a new node as the right child of the current node and make the current node equal to the right child.
If the current token is an operand, set the current node''s data value to the operand and make the current node equal to the parent by popping the stack.
If the current token is a right parenthesis make the current node equal to the parent node by popping the stack if it is not empty.
For the input file this is what your program will output:

( ( 8 + 3 ) * ( 7 - 2 ) ) = 55

Prefix Expression: * + 8 3 - 7 2

Postfix Expression: 8 3 + 7 2 - *
Posted Date: 4/20/2012 9:52:36 AM | Location : United States

Related Discussions:- Expression Tree, Assignment Help, Ask Question on Expression Tree, Get Answer, Expert's Help, Expression Tree Discussions

Write discussion on Expression Tree
Your posts are moderated
Related Questions
what is the code to copy code on 1 jsp page to others

Redundant sequence identification: Given a set of k DNA sequences, S = { s 1, s 2, ... ,  s k } give an optimal algorithm to identify all sequences that are completely contained

Overview You will write a loadable kernel module. If you have an idea which you can convince me is a good idea that can not be done as a module, but only via direct modificatio

the details on the two pictures on the link below : ">

I have an assignment that requires from me to run multiple clients and one server ( Corba)

Write a Fortran LOGICAL FUNCTION, called "is_prime", which determines if a given integer value is a prime number or not (A prime number is a natural number which has only two disti

Define Call by value - Computer Programming? Functions are raise by writing their name and an appropriate list of arguments within parenthesis. Usually these arguments are in t

Introduction Currently, Omega has 178 stores UK wide. Most cities and large towns within the UK are catered for by Omega. Omega began in 1960's selling various makes of telep

Explain the Break Statement - Computer Programming? The break statement is used as an interrupt to the normal flow of control this statement causes as exit from the switch stat

Applications of OOP, The promising areas for application of OOP include: Real-time systems Simulation and modelling Object-oriented databases Hypertext, hype