本文實(shí)例為大家分享了python正則實(shí)現(xiàn)計(jì)算器功能的具體代碼，供大家參考，具體內(nèi)容如下 # -*- coding: utf-8 -*-

# Author :Gogh

# @Time :2017/12/4 20:16

# @Email :361910002@qq.com

import re

def operator_update(formula):

# 對(duì)formula公式進(jìn)行 去除空字符，更新運(yùn)算符處理

formula = formula.replace(" ", "") # 去除空字符

formula = formula.replace("+-", "-")

formula = formula.replace("--", "+")

return formula

def calc_muldiv(formula_list):

'''''

計(jì)算公式里面的乘除

:param formula: 列表

:return:

'''

for index, element in enumerate(formula_list):

if "*" in element or "/" in element:

operators = re.findall("[*/]", element)

calc_list = re.split("[*/]", element)

num = None

for i, e in enumerate(calc_list):

if num:

if operators[i - 1] == "*":

num *= float(e)

elif operators[i - 1] == "/":

num /= float(e)

else:

num = float(e)

formula_list[index] = num

return formula_list

def calc_plumin(operators, num_list):

'''''

計(jì)算列表數(shù)字的加減

:param operators: 運(yùn)算符列表

:param num_list: 進(jìn)行運(yùn)算的數(shù)字列表

:return: 返回計(jì)算結(jié)果

'''

num = None

for i, e in enumerate(num_list):

if num:

if operators[i - 1] == "+":

num += float(e)

elif operators[i - 1] == "-":

num -= float(e)

else:

num = float(e)

return num

def merge(plus_minus_operator, multiply_divide_list):

'''''

把列表中這樣的形式'2*' '-3*' '5/3*' '4/2'合并到一塊

:param formula_list:

:return:

'''

for index, element in enumerate(multiply_divide_list):

if element.endswith("*") or element.endswith("/"):

multiply_divide_list[index] = element + plus_minus_operator[index] + multiply_divide_list[index + 1]

del multiply_divide_list[index + 1]

del plus_minus_operator[index]

return merge(plus_minus_operator, multiply_divide_list)

return plus_minus_operator, multiply_divide_list

def bracket_calc(formula):

'''''

對(duì)括號(hào)最內(nèi)層的formula公式進(jìn)行計(jì)算

:param formula:

:return:

'''

formula = re.sub("[()]", "", formula) # 去除兩邊的()

formula = operator_update(formula)

plus_minus_operator = re.findall("[+-]", formula) # 列表 '+' '-' 運(yùn)算符

multiply_divide_list = re.split("[+-]", formula) # 列表 有'*' '/'

if multiply_divide_list[0] == "": # multiply_divide_list列表第一個(gè)字符為空的話，表示一個(gè)數(shù)字為負(fù)號(hào)

multiply_divide_list[1] = "-" + multiply_divide_list[1]

del plus_minus_operator[0]

del multiply_divide_list[0]

res = merge(plus_minus_operator, multiply_divide_list)

plus_minus_operator = res[0] # 列表 '+' '-' 運(yùn)算符 進(jìn)行合并處理

multiply_divide_list = res[1]

plus_minus_list = calc_muldiv(multiply_divide_list) # 生成只進(jìn)行加減運(yùn)算的列表

res = calc_plumin(plus_minus_operator, plus_minus_list)

return res

def calculate(formula):

'''''計(jì)算程序主入口, 主要邏輯是先計(jì)算拓號(hào)里的值,算出來(lái)后再算乘除,再算加減'''

while True:

formula_depth = re.search("[()]+", formula)

if formula_depth:

formula_depth = formula_depth.group()

res = bracket_calc(formula_depth)

formula = formula.replace(formula_depth, str(res))

print("\33[34;1m%s\33[0m" % (formula))

else:

res = bracket_calc(formula)

print("\33[31;1m結(jié)果:%s\33[0m" % (res))

exit()

if __name__ == '__main__':

formula = "1 - 2 * ( (60-30 +(-9-2- 5-2*-3-5/3-40*4/2-3/5+6*3) * (-9-2-5-2*5/3 + 7 /3*99/4*2998 +10 * 568/14 )) -(-4*3)/ (16-3*2) )"

calculate(formula)

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