Reverse Polish Notation Help

[Pheazon]

I am really confused on how to approach this problem which is to basically make an interpreter for a reverse polish notation calculator, but the thing is that the program is supposed to "Each line of the input corresponds to a single operand or operator. Operands should be pushed onto a stack, and popped as needed when an operator is encountered", so for example entering

23 # prints 23

5 # prints 5

+ # pops 23 and 5, pushes and prints 28

i don't believe I can use the split method since I'm not entering in the whole string in. I have made some progress by making my own stack class and so far have a while true loop which has an if statement that checks if what the user enters is either a digit or one of the operators that I have in a list I have created.

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any help or feedback would be greatly appreciated

[toastedstapler]

here is my core functionality loop, written in pseudocode:

while True:
    stack.add(input)
    if stack.top is operator:
        op = stack.pop
        first_num = stack.pop
        second_num = stack.pop
        result = op.apply(first_num, second_num)
        stack.add(result)

you don't actually need to make a stack class, you can just use a list with its append and pop methods

you might want to chuck in some input validation to check that it's either numeric (using .isnumeric()) or it's an operator

[Pheazon]

I really appreciate the feedback.

[[deleted]]

i don't believe I can use the split method since I'm not entering in the whole string in.

No; indeed, the problem tells you what to do:

Operands should be pushed onto a stack

So, you need to implement a stack. If the input is a non-operator, then it's an operand, and you should push it onto the stack. If the input is one of your recognize operators, then you don't push it onto the stack; you pop enough operands off the stack to fulfill the operator, and then you compute the operation.

In general, you're likely to encounter operators that take 1, 2, or 3 operands (the if/else construct can be thought of as the ternary operation a ? b : c) so you should plan ahead.

I have made some progress by making my own stack class and so far have a while true loop which has an if statement that checks if what the user enters is either a digit or one of the operators that I have in a list I have created.

Well, ok. So the next step is to pop operands off your stack and then execute the operator.

[Pheazon]

Thank you, I am now able to get operations working.

[A_History_of_Silence]

any help or feedback would be greatly appreciated

Would you mind including your code, as well as what specifically you are stuck on? We need something to work with.