python 计算器

计算器 等式

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# @File  : calculators.py
# @Author: Anthony.waa
# @Date  : 2018/8/13 0013
# @Desc  :

example = '- 2 * ( (60-30 +(-40/5) * (9-2*5/3 + 7 /3*99/4*2998 +10 *568/14 )) - (-4*3)/ (16-3*2) )'


import re

bracket = re.compile(r'\([^()]+\)') # 找括号
multiplys = re.compile(r'(\d+\.?\d*\*-\d+\.?\d*)|(\d+\.?\d*\*\d+\.?\d*)')   # 找乘法
divides = re.compile(r'(\d+\.?\d*/-\d+\.?\d*)|(\d+\.?\d*/\d+\.?\d*)')   # 找除法
adds = re.compile(r'(-?\d+\.?\d*\+-\d+\.?\d*)|(-?\d+\.?\d*\+\d+\.?\d*)')    # 找加法
subtracts = re.compile(r'(-?\d+\.?\d*--\d+\.?\d*)|(-?\d+\.?\d*-\d+\.?\d*)') # 找减法
out_cal = re.compile(r'\(?\+?-?\d+\)?') # 验证等式是否计算完成
out_strip = re.compile(r'[^(].*[^)]')   # 去除最后括号


def Add(s):  # 加法运算
    result = re.split(r'\+', adds.search(s).group())
    return s.replace(adds.search(s).group(), str(float(result[0]) + float(result[1])))


def Subtract(s):  # 减法运算
    result = subtracts.search(s).group()
    if result.startswith('-'):
        result = result.replace('-', '+')
        res = Add(result).replace('+', '-')
    else:
        result = re.split(r'-', result)
        res = str(float(result[0]) - float(result[1]))
    return s.replace(subtracts.search(s).group(), res)


def Multiply(s):  # 乘法运算
    result = re.split(r'\*', multiplys.search(s).group())
    return s.replace(multiplys.search(s).group(), str(float(result[0]) * float(result[1])))


def Divide(s):  # 除法运算
    result = re.split(r'/', divides.search(s).group())
    return s.replace(divides.search(s).group(), str(float(result[0]) / float(result[1])))


def calculatoring():  # 开始计算
    while True:
        print('-'*90)
        print('提示: 输入(q/exit/n),任意一个即可退出运算')
        print('例如: - 2 * ( (60-30 +(-40/5) * (9-2*5/3 + 7 /3*99/4*2998 +10 *568/14 )) - (-4*3)/ (16-3*2) )')
        beginning = input('请输入一个符合加减乘除法运算的等式:').strip()
        if beginning.lower() == 'q' or beginning.lower() == 'exit' or beginning.lower() == 'n':
            break
        else:
            beginning = ''.join([i for i in re.split('\s+', beginning)])  # 去除等式中的空格
            if not beginning.startswith('('):
                beginning = str('(%s)' % beginning)
                while bracket.search(beginning):  # 循环计算括号中的等式
                    beginning = beginning.replace('--', '+')
                    beginning_search = bracket.search(beginning).group()  # 正式开始等式计算   beginning.....
                    # 计算顺序 除法--> 乘法 --> 减法 --> 加法
                    if divides.search(beginning_search):  # 除法
                        beginning = beginning.replace(beginning_search, Divide(beginning_search))
                    elif multiplys.search(beginning_search):  # 乘法
                        beginning = beginning.replace(beginning_search, Multiply(beginning_search))
                    elif subtracts.search(beginning_search):    # 减法
                        beginning = beginning.replace(beginning_search,Subtract(beginning_search))
                    elif adds.search(beginning_search): # 加法
                        beginning = beginning.replace(beginning_search,Add(beginning_search))
                    elif out_cal.search(beginning_search):  # 去除最后的括号 查看等式运算是否计算完毕
                        beginning = beginning.replace(beginning_search,out_strip.search(beginning_search).group())
                print('该等式计算结果约为:%.2f'%float(beginning))
                print()


if __name__ == '__main__':
    calculatoring()