Chapter 18, Problem 8PC

Program Plan Intro

Stack Copy Operations

Program Plan:

• Declare the main function.
  • Prompt the user to enter a postfix expression.
  • Convert an input stream into a string stream.
  • Evaluate the postfix expression by calling the postfixExpr function and print the result.
• Skip whitespace in an input stream while evaluating a postfix expression.
• Declare a Function postfixExpr that evaluates the postfix expression by considering if the next token in the input stream is an integer, read  the integer and push it onto the stack using the push() operation of the stack .
  • However, if the input stream is an operator, pop the last two values from the stack using the pop operation and apply the operator, and push the result onto the stack and the lone value is the result and look for next iteration.