How to implement a simple calculator?

[Uninverted]

I'm writing a really really simple calculator (Basically just for the heck of it) and I'm not sure exactly how to implement it. I was thinking of using Lex or something else for creating compilers, but I don't want to learn a new tool just for a fairly trivial program like this. I also thought of using straight C, but I honestly just don't like C (All my C programs fail randomly, it seems like it doesn't like me either). I've pretty much decided on writing a regex validator in Perl or Python (something like "/\d+ *[+\-*\/] *\d+/" so it doesn't try to solve "Hamburger") then passing that to some fast compiled language (like C or Pascal or something) whether by making a function that's accessible in the high level language or making the overarching program a shell script (I don't want to do this) and then finally sending the result to stdout. I might just do the whole thing in Perl or Python, which has the big advantage of making the whole thing one standalone program.

[Xav]

What's wrong with C? Try C# - it's great, and really powerful. You can use any .NET language, and I'm happy.

[Uninverted]

Originally Posted by Xav

What's wrong with C? Try C# - it's great, and really powerful. You can use any .NET language, and I'm happy.

Not really an option; I use Linux, and this program's meant to be just a small Unix filter (works well with redirection & pipes). And this type of program goes fast enough to use a slow interpreted language for just about any of thew parts, if necessary; integer arithmetic might be the easiest thing for a computer to do, and I've already written the regex tester (just prints "Valid" or "Invalid" right now), and it's practically instant.

EDIT: Nevermind, I did it in literally 10 lines of Python. I love Python.

[zorocke]

I am wondering what your code looks like because I am still very unfamiliar with Python. Do you think you could post those 10 lines?

[Uninverted]

Originally Posted by zorocke

I am wondering what your code looks like because I am still very unfamiliar with Python. Do you think you could post those 10 lines?

Sure, always glad to help a new pythonist.

#!/usr/bin/python
import re #Import the regular expression module

pat = re.compile('\d+ *[+\-*\/] *\d+') #Set up the Regex pattern for a math problem
prob = raw_input() #Get the problem

if pat.match(prob):
    print eval(prob) #Print the evaluated problem, but only if it matches the pattern
else:
    print "Invalid math problem" #If it doesn't, then it isn't a math problem

But if you reduce it to the absolute minimum, you can do it in one line!

eval(raw_input())

[Xav]

Originally Posted by Uninverted

Not really an option; I use Linux, and this program's meant to be just a small Unix filter (works well with redirection & pipes). And this type of program goes fast enough to use a slow interpreted language for just about any of thew parts, if necessary; integer arithmetic might be the easiest thing for a computer to do, and I've already written the regex tester (just prints "Valid" or "Invalid" right now), and it's practically instant.

EDIT: Nevermind, I did it in literally 10 lines of Python. I love Python.

Oh, all right then, I suppose Python is pretty cool. Did you know there's a library called Pygame, that you can use to create games using Python? I know Python's a tad slow, but Pygame's built on a C Game Library, so it's pretty fast.

Just thought it might be interesting. And the best part - you get to play your Python games when you've finished writing them!

Python + Speed + Game Creation = Pygame + Ultimate Joy

Xav :-)