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Re: Creating a calculator

Path csiph.com!feeder.erje.net!2.eu.feeder.erje.net!fu-berlin.de!uni-berlin.de!not-for-mail
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=raw_input('Enter calculation to perform: ')
>> n1=float(ui.split(' ')[0])
>> op=ui.split(' ')[1]
>> n2=float(ui.split(' ')[2])
>> if op=='+':c=n1+n2
>> if op=='-':c=n1-n2
>> if op=='*':c=n1*n2
>> if op=='/':c=n1/n2
>> print(ui+' = '+str(c))
>> -----------------------------------------------
>
> More reduced :
> ----------------------------------
> u=raw_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’s a great way to compromise your system’s
security. Never use eval() for any reason, especially with user input
— if you were to type in __import__('os').system('…') with some
particularly dangerous command (rm, format, …), you would kill your
system.

-- 
Chris Warrick <https://chriswarrick.com/>
PGP: 5EAAEA16

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Thread

Creating a calculator Elizabeth Weiss <cake240@gmail.com> - 2016-06-30 20:08 -0700
  Re: Creating a calculator Michael Torrie <torriem@gmail.com> - 2016-06-30 21:38 -0600
  Re: Creating a calculator DFS <nospam@dfs.com> - 2016-06-30 23:57 -0400
  Re: Creating a calculator DFS <nospam@dfs.com> - 2016-07-01 00:54 -0400
    Re: Creating a calculator Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-07-01 09:42 +0300
      Re: Creating a calculator Christopher Reimer <christopher_reimer@icloud.com> - 2016-07-01 05:25 -0700
        Re: Creating a calculator Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-07-01 15:46 +0300
          Re: Creating a calculator Christopher Reimer <christopher_reimer@icloud.com> - 2016-07-01 06:19 -0700
            Re: Creating a calculator Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-07-01 16:35 +0300
        Re: Creating a calculator Steven D'Aprano <steve@pearwood.info> - 2016-07-01 23:52 +1000
          Re: Creating a calculator alister <alister.ware@ntlworld.com> - 2016-07-01 14:21 +0000
          Re: Creating a calculator Christopher Reimer <christopher_reimer@icloud.com> - 2016-07-01 07:15 -0700
          Re: Creating a calculator Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-07-01 20:44 +0300
          Re: Creating a calculator Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-07-04 12:32 +0200
      Re: Creating a calculator DFS <nospam@dfs.com> - 2016-07-01 20:16 -0400
    Re: Creating a calculator pdorange@pas-de-pub-merci.mac.com (Pierre-Alain Dorange) - 2016-07-01 11:34 +0200
      Re: Creating a calculator Chris Warrick <kwpolska@gmail.com> - 2016-07-01 13:39 +0200
        Re: Creating a calculator pdorange@pas-de-pub-merci.mac.com (Pierre-Alain Dorange) - 2016-07-01 15:03 +0200
      Re: Creating a calculator DFS <nospam@dfs.com> - 2016-07-01 20:16 -0400
        Re: Creating a calculator pdorange@pas-de-pub-merci.mac.com (Pierre-Alain Dorange) - 2016-07-04 11:50 +0200
        Re: Creating a calculator BartC <bc@freeuk.com> - 2016-07-06 01:53 +0100
          Re: Creating a calculator Quivis <quivis@domain.invalid> - 2016-07-07 22:00 +0000
  Re: Creating a calculator Chris Warrick <kwpolska@gmail.com> - 2016-07-01 10:57 +0200

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