[Solved]A little calculator writed in Python.

SpeedVin · 2009-09-22 15:06:34

Hello.
I started to write programs in Python and I really like it (Python).
i want to start programming in Python from make a little calculator program (You can use it without X).
And I got all things but I don't know how to write a action that python will read + or - I writedhow to input a nuber to program but I don't know how input + to my program .
Thanks for advice or help.

Last edited by SpeedVin (2009-09-22 18:18:58)

g0ju · 2009-09-22 15:13:16

Could you be more specific? What do you have so far and what's your programm supposed to do?

SpeedVin · 2009-09-22 15:20:14

g0ju wrote:

Could you be more specific? What do you have so far and what's your programm supposed to do?

He have to calculate.
2 + 3
or
2 * 3
For now he understand how to read inputed numbers but don't know about how to read sign like I input 2 as first number and 2 as second and I want to sum that 2 numbers

Xyne · 2009-09-22 15:31:24

It depends on how you're getting user input. Are you accepting arguments on the command line or are you reading them interactively in your code?

It would help if you posted the actual code that you have already so that we can see what you're doing. General descriptions are usually not very useful when trying to help someone with code.

SpeedVin · 2009-09-22 16:56:04

That's the code of my program:

  1 #!/usr/bin/env python
  2 # -*- coding: utf-8 -*-
  3 
  4 number1 = int(raw_input('Write a number: '))
  5 number2 = int(raw_input('Write a number nr.2: '))
  6 znak = int(raw_input('What to do?'))
  7 print number1 + number2

Last edited by SpeedVin (2009-09-22 17:01:03)

Xyne · 2009-09-22 18:12:01

Remove the "int()" call that's wrapping the third input. "int()" converts its argument to an integer.

Try something like this:

#!/usr/bin/env python
# -*- coding: utf-8 -*-

number1 = int(raw_input('Write a number: '))
number2 = int(raw_input('Write a number nr.2: '))
znak = raw_input('What to do?')
if znak == '+':
    print number1 + number2
elif znak == '-':
    print number1 - number2
else:
    print "I don't know what to do with " + znak

Of course this would be impractical as the number of operations increases, but discovering a better way to do it is part of the learning experience.

*edited for typos*

Last edited by Xyne (2009-09-22 18:15:17)

SpeedVin · 2009-09-22 18:18:32

Xyne wrote:

Remove the "int()" call that's wrapping the third input. "int()" converts its argument to an integer.
Try something like this:
#!/usr/bin/env python
# -*- coding: utf-8 -*-

number1 = int(raw_input('Write a number: '))
number2 = int(raw_input('Write a number nr.2: '))
znak = raw_input('What to do?')
if znak == '+':
    print number1 + number2
elif znak == '-':
    print number1 - number2
else:
    print "I don't know what to do with " + znak
Of course this would be impractical as the number of operations increases, but discovering a better way to do it is part of the learning experience.
*edited for typos*

Thanks Xyne it's so simple!

XFire · 2009-09-22 18:19:06

It would be better if you requested the equation as a string, then by using regular expressions, deem what is required of the program. Alternatively, you could do something similar but tokenise the string, splitting it up into first number, the operator and then the second number.

Barrucadu · 2009-09-22 18:24:53

XFire wrote:

It would be better if you requested the equation as a string, then by using regular expressions, deem what is required of the program. Alternatively, you could do something similar but tokenise the string, splitting it up into first number, the operator and then the second number.

I'd just use eval().

Xyne · 2009-09-22 19:16:13

I thought of eval too, but that introduces security issues (same as "input").
You could even argue that you can skip the code and use python's shell directly, but that defeats the purpose of learning.

I had some other thoughts too, but I'm leaving them unsaid. This is a one-man bikeshed until the next problem arises

Arch Linux

#1 2009-09-22 15:06:34

[Solved]A little calculator writed in Python.

#2 2009-09-22 15:13:16

Re: [Solved]A little calculator writed in Python.

#3 2009-09-22 15:20:14

Re: [Solved]A little calculator writed in Python.

#4 2009-09-22 15:31:24

Re: [Solved]A little calculator writed in Python.

#5 2009-09-22 16:56:04

Re: [Solved]A little calculator writed in Python.

#6 2009-09-22 18:12:01

Re: [Solved]A little calculator writed in Python.

#7 2009-09-22 18:18:32

Re: [Solved]A little calculator writed in Python.

#8 2009-09-22 18:19:06

Re: [Solved]A little calculator writed in Python.

#9 2009-09-22 18:24:53

Re: [Solved]A little calculator writed in Python.

#10 2009-09-22 19:16:13

Re: [Solved]A little calculator writed in Python.

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