Need to write a program that evaluates a postfix expression which is input by the user and then displays the answer.

For example, if the user inputs 493*+ then the program should evaluate this postfix expression and display the answer. The user input can vary and the total number of characters may also vary. So, this should also be taken into consideration while writing the program. Thanks!

[Walter Roberson]

http://www.mathworks.com/matlabcentral/answers/6200-tutorial-how-to-ask-a-question-on-answers-and-get-a-fast-answer

Answer 1

[Bjorn Gustavsson]

If you want us to do your assignments you might have a better chance if you explicitly ask us to. What have you done so far?

Small tip: if current character (token rather!) is a number put it on a stack, if it is an operator take contents of stack and perform operation on those.

HTH

[naveen selvan]

Thanks for the reply. But, I am unable to convert a postfix expression into individual characters. For example, if the user inputs 123*+ as the postfix expression, I am currently storing it as a string. But, then I am unable to read the string by one character at a time. So, I am stuck right there. If I could read the individual characters, I could solve the rest as the logic is quite simple. Pls help!

[Walter Roberson]

current_position = 5
current_character = input_string(current_position)
if current_character == '0'
  ... do something appropriate
elseif current_character == '2'
  .... do something appropriate
elseif current_character == '{'
  ... do something appropriate
elseif current_character == '⁞'
  ... do something appropriate
end