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class Stack_calc(object):
'''Stack calulator - push numbers into stack - calculate last 2 elements'''
def __init__(self):
self.item = []
self.calculate =\
{'+' : lambda: self.item.append(self.item.pop() + self.item.pop()),
'-' : lambda: self.item.append(self.item.pop() - self.item.pop()),
'*' : lambda: self.item.append(self.item.pop() * self.item.pop()),
'/' : lambda: self.item.append(self.item.pop() / self.item.pop()),}
def parse_stack(self, source):
stack = source.split()
for element in stack:
try:
self.item.append(float(element))
except ValueError:
if element in self.calculate:
try:
self.calculate[element]()
except IndexError:
pass
def __str__(self):
return str(self.item)
def main():
obj = Stack_calc()
#Enter number will add to stack,use operators +-*/ to calculate 2 last elements
#To exit type Q
while True:
into_stack = raw_input(':-> ')
if into_stack == 'Q':
break
obj.parse_stack("%s" % into_stack)
print obj
if __name__ == '__main__':
main()
>>> :-> 1 [1.0] :-> 2 [1.0, 2.0] :-> 3 [1.0, 2.0, 3.0] :-> 4 [1.0, 2.0, 3.0, 4.0] :-> 5 [1.0, 2.0, 3.0, 4.0, 5.0] :-> + [1.0, 2.0, 3.0, 9.0] :-> - [1.0, 2.0, 6.0] :-> * [1.0, 12.0] :-> / [12.0] :-> / [] :-> 10000 [10000.0] :-> 2222 44444 [10000.0, 2222.0, 44444.0] :-> 5555 [10000.0, 2222.0, 44444.0, 5555.0] :-> 900000000 [10000.0, 2222.0, 44444.0, 5555.0, 900000000.0] :-> / [10000.0, 2222.0, 44444.0, 162016.20162016203] :-> * [10000.0, 2222.0, 7200648064.806481] :-> + [10000.0, 7200650286.806481] :-> - [7200640286.806481] :-> - [] :-> Q >>>
class Stack_calc(object):
'''Stack calulator'''
def __init__(self):
self.item = []
self.calculate =\
{'+' : lambda: self.item.append(self.item.pop() + self.item.pop()),
'-' : lambda: self.item.append(self.item.pop() - self.item.pop()),
'*' : lambda: self.item.append(self.item.pop() * self.item.pop()),
'/' : lambda: self.item.append(self.item.pop() / self.item.pop())}
def parse_stack(self, source):
self.stack = source.split()
for num in self.stack:
try:
self.item.append(float(num))
except ValueError:
for element in self.stack:
if element in ['+','-','*','/'] and len(self.item) > 1:
self.calculate[element]()
else:
try:
d = {'+': self.item[0] + self.item[0],'-': self.item[0] - self.item[0],
'*': self.item[0] * self.item[0],'/': self.item[0] / self.item[0]}
if element in d:
self.item[0] = d[element]
except (IndexError,ZeroDivisionError):
pass
def __str__(self):
return str(self.item)
def main():
'''Enter numbers,will be added to a stack
use operators +-*/ to calculate 2 last elements
To exit type Q
'''
obj = Stack_calc()
while True:
into_stack = raw_input(':-> ')
if into_stack == 'Q':
break
obj.parse_stack("%s" % into_stack)
print obj
if __name__ == '__main__':
main()
>>> :-> 1 [1.0] :-> 2 [1.0, 2.0] :-> 3 [1.0, 2.0, 3.0] :-> 4 [1.0, 2.0, 3.0, 4.0] :-> 5 [1.0, 2.0, 3.0, 4.0, 5.0] :-> + [1.0, 2.0, 3.0, 9.0] :-> - [1.0, 2.0, 6.0] :-> * [1.0, 12.0] :-> / [12.0] :-> - [0.0] :-> 1 [0.0, 1.0] :-> + [1.0] :-> + [2.0] :-> + [4.0] :-> * [16.0] :-> 1000 [16.0, 1000.0] :-> 500.25 147 0.899 [16.0, 1000.0, 500.25, 147.0, 0.899] :-> * [16.0, 1000.0, 500.25, 132.153] :-> * [16.0, 1000.0, 66109.53825] :-> / [16.0, 66.10953825] :-> / [4.131846140625] :-> - [0.0] :->
.)
#!/usr/bin/env python3
ops = {'*': lambda x, y: x * y, '+': lambda x, y: x + y,
'/': lambda x, y: x / y, '-': lambda x, y: x - y}
stack = []
while True:
x = input(':-> ')
if x in ops:
if len(stack) == 1:
stack.append(stack[0])
stack.append(ops[x](stack.pop(), stack.pop()))
else:
try:
stack.append(float(x))
except ValueError:
print("Invalid number or operator.")
print(stack)
import System.IO (hFlush, stdout)
import Data.Maybe
ops = [("*", (*)), ("+", (+)), ("/", (/)), ("-", (-))]
handle x ys | isJust op = case ys of (y:y':ys') -> op' y' y : ys'
(y:ys') -> op' y y : ys'
_ -> error "Empty stack."
| otherwise = read x : ys
where op = lookup x ops
op' = fromJust op
run st = do putStr ":-> "
hFlush stdout
x <- getLine
let st' = handle x st
print st'
run st'
main = run []
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