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From: Chris Warrick <kwpolska@gmail.com>
Newsgroups: comp.lang.python
Subject: Re: Creating a calculator
Date: Fri, 1 Jul 2016 13:39:39 +0200
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On 1 July 2016 at 11:34, Pierre-Alain Dorange
<pdorange@pas-de-pub-merci.mac.com> wrote:
> DFS <nospam@dfs.com> wrote:
>
>> Here's a related program that doesn't require you to tell it what type
>> of operation to perform.  Just enter 'num1 operator num2' and hit Enter,
>> and it will parse the entry and do the math.
>>
>> -----------------------------------------------
>> ui=3Draw_input('Enter calculation to perform: ')
>> n1=3Dfloat(ui.split(' ')[0])
>> op=3Dui.split(' ')[1]
>> n2=3Dfloat(ui.split(' ')[2])
>> if op=3D=3D'+':c=3Dn1+n2
>> if op=3D=3D'-':c=3Dn1-n2
>> if op=3D=3D'*':c=3Dn1*n2
>> if op=3D=3D'/':c=3Dn1/n2
>> print(ui+' =3D '+str(c))
>> -----------------------------------------------
>
> More reduced :
> ----------------------------------
> u=3Draw_input('Enter calculation:")
> print eval(u)
> ----------------------------------
> works and compute :
> 1+2+3+4-1+4*2
> 2+3.0/2-0.5
>
> Perform better and shorter, but less educationnal of course...

No, this is awful. It=E2=80=99s a great way to compromise your system=E2=80=
=99s
security. Never use eval() for any reason, especially with user input
=E2=80=94 if you were to type in __import__('os').system('=E2=80=A6') with =
some
particularly dangerous command (rm, format, =E2=80=A6), you would kill your
system.

--=20
Chris Warrick <https://chriswarrick.com/>
PGP: 5EAAEA16