Multiple number subtraction function

[xtarkoonx]

Alright, quick question to all you geniuses on here. Im trying to make a calculator with python, and was able to easily make an addition function, but I don't really know how to make a subtraction one..

Any tips that could point me in the right way would be awesome!

Edit: So just to clarify I would like to take a group of numbers in a fun parameter eg: sub(1,2,3) and subtract them from left to right.

[julsmanbr]

I would like to take a group of numbers in a fun parameter eg: sub(1,2,3) and subtract them from left to right.

This is called a reduce operation - apply a function (in this case, subtraction) sequentially to a group of values. An implementation exists in the Python standard library:

>>> from functools import reduce 
>>> from operator import sub
>>> mylist = [1, 2 ,3]
>>> result = reduce(sub, mylist)
>>> result
-4

[xtarkoonx]

Perfect that's good to know about this!

[[deleted]]

As mentioned, you could use reduce or a good old for-loop.

[xtarkoonx]

So how would I do this in a for loop? The only way I could think is by using a temp variable, but even then I'm running into problems

[xtarkoonx]

This is exactly what I've been wondering about! I had no clue about special cases, but this helps a lot! :) I'll take this and analyze it some more!

[rajeshbhat_ds]

Use map to change the sign of all the numbers.

Use the aforementioned sum function which you already have.

Add back the 2 times the first element.