Chapter 20, Problem 20.16PE

Program Plan Intro

Convert infix to postfix expression

Program plan:

• Import the required packages into the program.
• In the Exercise20_16 class,
  • In the main() method,
    • Check the length of arguments is less than 1. If yes, display the error message.
    • The for loop executes until length of arguments. If yes, assign the inputs into variable.
    • In try block,
      • Call infixToPostfix() method to convert the infix to postfix expression.
    • Catch the exception.
  • In the infixToPostfix() method,
    • Create two operandStack to store operands.
    • Extract the operands and operators.
    • The while loop execute until the token. If yes,
      • Read the token only and store into string variable.
      • Check whether the length of token is equal to 0. If yes, continue the code.
      • Otherwise, check index "0" is equal to "+" or "-". If yes,
        • Loop executes until process all +, -, *, / in the top of stack. If yes,
          • Call pop() method to remove the operator from stack and then store into variable.
        • Call push() to add the + or - operator into the stack.
      • Otherwise, check index "0" is equal to "*" or "/". If yes,
        • Loop executes until process all *, / in the top of stack. If yes,
          • Call pop() method to remove the operator from stack and then store into variable.
        • Call push() to add the * or / operator into the stack.
      • Otherwise, check index "0" is equal to "(". If yes, call push() method to push the symbol to stack.
      • Otherwise, check index "0" is equal to ")". If yes, call pop() to remove the “(” symbol from the stack.
    • Otherwise, push an operand to stack.
    • The while loop executes until process all the remaining operators in stack. If yes, call pop() method to remove the operator from stack.
    • Return the result.