Math problem in Python - pyqt5

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Math problem in Python - pyqt5 - rwahdan - Jun-18-2019

Hi,

I have a calculator project, I am able to give 2 numbers and operator to get answer after pressing = sign. Example, 1+2=3. Now, what if the user keeps adding operators before pressing the = sign. Example, 1+2+3+4+5+6+7=answer. how to track them all? I have a function that will take the first operation 1+2 passing 2 variables and an operator. How can I deal with such problem if the list is long before pressing the = sign?

def math(val1,operator,val2):
    if operator = "+":
        return val1+val2
    elif operator = "-":
        return val1-val2

this is if the operation is taking 2 values, how to deal with this if it is more than that.

RE: Math problem in Python - pyqt5 - ichabod801 - Jun-18-2019

What have you tried?

RE: Math problem in Python - pyqt5 - michalmonday - Jun-18-2019

Hi, you could use eval(string)

Quote:>>> eval("1+2+3")
6

https://docs.python.org/3/library/functions.html#eval

RE: Math problem in Python - pyqt5 - ThomasL - Jun-18-2019

(Jun-18-2019, 03:44 PM)michalmonday Wrote: Hi, you could use eval(string)

If proposing eval() you should also provide this warning information.

RE: Math problem in Python - pyqt5 - ichabod801 - Jun-18-2019

And given that this is in the homework section, I seriously doubt the teacher is going to accept eval as a valid answer.

RE: Math problem in Python - pyqt5 - noisefloor - Jun-18-2019

Hi,

eval is evil, don't do that.

@rwahdan: in case your calculator has to accept a long(er) operation like 1+2+3+4, put the operation in a list, iterate over the list and make the calculations.

When you think about it, you can make it even more complicated, like 1+2*3 is mathematically correct 1+(2*3) = 7 - but if you would evaluate plain left to right, you would get 9... Do you want to / have to deal with invalid input like 1+-3?

Regards, noisefloor

RE: Math problem in Python - pyqt5 - Gribouillis - Jun-18-2019

The

if operator = '+':

is not valid python code. Please post code that runs for real in the python interpreter.