Question

Python:
So I am working on a program (which is a class assignment) that will take an expression such as 3/4/5 or 32432/23423/2354325 or 3425*343/254235 or 43252+34254-2435, etc(for all operators from +,-,/,*). and will solve the expression.

I CANT USE EVAL!!

I cant use higher level codes, I am limited to, at most, using string manipulators from the below website to split the string.

http://docs.python.org/2/library/stdtypes.html#typesseq

My method is to look at the expression the user enters and then use a find function to find the OPERATORS, and then use these operators and a slicing function (eg. s[0:x]). What I have is below and unfortunately it isnt working: *note that the print statements are in there for debugging purposes only.
EDIT: why is x not defined when I run the program and enter an expression?

z= (input("expression:")).strip()

def finding(z):
    if "/" in z:
        x=z.find("/")
        print("hi1")
    elif "*" in z:
        x=z.find("*")
        print("hi2")
    elif "+" in z:
        x=z.find("+")
        print("hi3")
    elif "-" in z:
        x=z.find("-")
        print("hi4")
    else:
        print("error, not math expression")
    return x

def Parsing(z,x):

    x= finding(z)
    qw=z.s[0:x]
    print (qw)
# take the x-value from function finding(z) and use it to split 

finding(z)
Parsing(z,x)

Answer 1

If you’re just having trouble splitting the input into its parts, here’s something to help you. I left it as readable as I could so that you could at least understand what it does. I’ll explain any part of it if you need me to:

def parse(text):
    chunks = ['']

    for character in text:
        if character.isdigit():
            if chunks[-1].isdigit():   # If the last chunk is already a number
                chunks[-1] += character  # Add onto that number
            else:
                chunks.append(character) # Start a new number chunk
        elif character in '+-/*':
            chunks.append(character)  # This doesn't account for `1 ++ 2`.

    return chunks[1:]

Example usage:

>>> parse('123 + 123')
['123', '+', '123']
>>> parse('123 + 123 / 123 + 123')
['123', '+', '123', '/', '123', '+', '123']

I’ll leave the rest up to you. If you aren’t allowed to use .isdigit(), you’ll have to replace it with lower-level Python code.