Python简易项目 加减计算器的实现

Python Calculator 1.0

支持功能：add、minus

输入表达式不含括号，允许不加'='

非常简单的一个小计算器，还缺少很多功能，目的是为了练练手。

日后会对其进行更新。

源码

Github：calculator1.0

#!/usr/bin/env python3

"""

	Name: Python Calculator 1.0

	Support: add minus

	Created by Chen. 2017/2/8

"""

def calculator(stack):

	s1, s2 = [], []

	# handle the stack

	for i in stack:

		if i == '+' or i == '-' :

			s1.append(i)

		else :

			s2.append(int(i))

	s3, s4 = [], []

	# turn the list

	while len(s1) > 0 :

		s3.append(s1[-1])

		s1.pop()

	while len(s2) > 0 :

		s4.append(s2[-1])

		s2.pop()

	# calculate the result

	while len(s3) > 0 :

		cal, mid = s3[-1], 0

		if cal == '+' :

			mid = s4[-1]+s4[-2]

			s4.pop()

			s4.pop()

			s4.append(mid)

		elif cal == '-' :

			mid = s4[-1]-s4[-2]

			s4.pop()

			s4.pop()

			s4.append(mid)

		s3.pop()

	return s4[-1]

def main():

	print('Python Calculator 1.0')

	calstr = input()

	mid, s1 = '', []

	for i in range(len(calstr)) :

		if (calstr[i] == '+' or calstr[i] == '-' or calstr[i] == '=') and i != 0:

			if mid != '' :

				s1.append(mid)

				mid = ''

			s1.append(calstr[i])

		else :

			mid = mid + calstr[i]

	if mid != '' :

		s1.append(mid)

	if s1[-1] == '=' : # delete '='

		s1.pop() 

	res = calculator(s1)

	print(res)

if __name__ == '__main__':

	main()

2017/2/8