[m0dem]

In this Python challenge, you will attempt to a make a CLI (Command Line Interface) calculator. Basically, what that means is: a calculator that can interpret simple math equations (e.g. 2+3-5*6 => -25). It must correctly compute addition, subtraction, multiplication, and division. It sounds simple, but it can get a little complicated at times. You cannot use eval() or anything like that, you MUST parse everything yourself.
I am really interested in what you come up with. Good luck!
151st post!

[m0dem]

Done!

Code:

import re def isMore(tokens): for t in tokens: if t == "*" or t == "/": return True return False def lex(equation): # remove all the whitespaces from the equation string equation = equation.replace(" ", "") return re.findall("[0-9]+|[\+, \-, \*, \/]", equation) def evaluate1(tokens, isOrigin = False): for i in range(0, len(tokens)): if tokens[i] == "*": a = int(tokens[i - 1]) * int(tokens[i + 1]) tokens = tokens[:i - 1] tokens.insert(i, a) break elif tokens[i] == "/": a = int(tokens[i - 1]) / int(tokens[i + 1]) tokens = tokens[:i - 1] tokens.insert(i, a) break if isMore(tokens): tokens = evaluate1(tokens) return tokens def evaluate2(tokens, isOrigin = False): if tokens[1] == "+": a = int(tokens[0]) + int(tokens[2]) tokens = tokens[3:] tokens.insert(0, a) elif tokens[1] == "-": a = int(tokens[0]) - int(tokens[2]) tokens = tokens[3:] tokens.insert(0, a) if len(tokens) > 1: tokens = evaluate2(tokens) if isOrigin: return tokens[0] else: return tokens equation = raw_input("Enter an equation: ") tokens = lex(equation) tokens = evaluate1(tokens, isOrigin = True) print(evaluate2(tokens, isOrigin = True))

And no, I didn't search up anything about this type of calculator for help.

[m0dem]

Well, since my last code was just a lame hack... I re-wrote it to make it much neater and more professional.
No recursion this time... too clunky.

Code:

import re def lex(equation): # remove all the whitespaces from the equation string equation = equation.replace(" ", "") return re.findall("[0-9]+|[\+, \-, \*, \/]", equation) def evalMulDiv(tokens): i = 0 while i < len(tokens): if tokens[i] == "*": tokens = tokens[:i - 1] + [int(tokens[i - 1]) * int(tokens[i + 1])] + tokens[i + 2:] i -= 2 elif tokens[i] == "/": tokens = tokens[:i - 1] + [int(tokens[i - 1]) / int(tokens[i + 1])] + tokens[i + 2:] i -= 2 i += 1 return tokens def evalAddSub(tokens): i = 0 while i < len(tokens): if tokens[i] == "+": tokens = tokens[:i - 1] + [int(tokens[i - 1]) + int(tokens[i + 1])] + tokens[i + 2:] i -= 2 elif tokens[i] == "-": tokens = tokens[:i - 1] + [int(tokens[i - 1]) - int(tokens[i + 1])] + tokens[i + 2:] i -= 2 i += 1 return tokens def calc(equation): tokens = lex(equation) tokens = evalMulDiv(tokens) return int(evalAddSub(tokens)[0]) equation = raw_input("> ") print(calc(equation))

@Megan! You try!
I think I will make a guide on CLI calculators soon. (possibly non-language specific -- pseudocode)

[meow]

I'm new to Python and don't really know how your script works. Mine sucks but I did my best. Don't know if this is what you were looking for or not.

Code:

def a(n1,n2): return float(n1 + n2) def s(n1,n2): return float(n1 - n2) def m(n1,n2): return float(n1 * n2) def d(n1,n2): return float(n1 / n2) c = raw_input("Operation? (add, sub, mult, div): ") n1 = float(raw_input("Enter the first number: ")) n2 = float(raw_input("Enter the second number: ")) if c == "add": print(a(n1,n2)) elif c == "sub": print(s(n1,n2)) elif c == "mult": print(m(n1,n2)) elif c == "div": print(d(n1,n2)) else: print("The operation you entered does not exist.")

[m0dem]

I'm new to Python and don't really know how your script works. Mine sucks but I did my best. Don't know if this is what you were looking for or not.

Code:

def a(n1,n2): return float(n1 + n2) def s(n1,n2): return float(n1 - n2) def m(n1,n2): return float(n1 * n2) def d(n1,n2): return float(n1 / n2) c = raw_input("Operation? (add, sub, mult, div): ") n1 = float(raw_input("Enter the first number: ")) n2 = float(raw_input("Enter the second number: ")) if c == "add": print(a(n1,n2)) elif c == "sub": print(s(n1,n2)) elif c == "mult": print(m(n1,n2)) elif c == "div": print(d(n1,n2)) else: print("The operation you entered does not exist.")

Well, that's not exactly what I was looking for. But it is okay; your did your best! Cool on you for learning Python though.
Basically, what I meant by a CLI calculator is that it takes a string such as "2 +8/2 * 4" and outputs the correct number (18). (note the use of operator precedence -- I do not require parentheses though)
Thanks for trying!!!

NOTE: Windows calc.exe doesn't even use operator precedence!?!?!

[Nil]

If you could explain your code that'd be cool, especially the eval functions.

Why tokens?

[m0dem]

If you could explain your code that'd be cool, especially the eval functions.

Why tokens?

Ok, I will make a separate guide on this.
Be looking for it.

---

I've finished!
https://www.sinister.ly/Thread-Tutorial-...ator-Works
Enjoy!

[Inori]

J:

Code:

".;2}input

Python (supports addition, subtraction, multiplication, division, exponents, and modulus):

Code:

import re import operator as op ops={'+': op.add,'-': op.sub,'*': op.mul,'/': op.div,'^': op.pow,'%': op.mod} while 1: e=raw_input('} ') for i in re.finditer('[\+,\-,\*,\/,\^,\%]',e): print ops[i.group()](int(e[:i.start()]),int(e[i.start()+1:]))

[m0dem]

J:

Code:

".;2}input

Python (supports addition, subtraction, multiplication, division, exponents, and modulus):

Code:

import re import operator as op ops={'+': op.add,'-': op.sub,'*': op.mul,'/': op.div,'^': op.pow,'%': op.mod} while 1: e=raw_input('} ') for i in re.finditer('[\+,\-,\*,\/,\^,\%]',e): print ops[i.group()](int(e[:i.start()]),int(e[i.start()+1:]))

Cool! Really compact code.
But.. your code can only do one operation per input. (you can't do "5+5*5" or "4*3-2*3")
You should be able to do an equation of arbitrary length.

[Inori]

Cool! Really compact code.
But.. your code can only do one operation per input. (you can't do "5+5*5" or "4*3-2*3")
You should be able to do an equation of arbitrary length.

I just got bored in history, I'll take it seriously and finish it later.