本文实例为大家分享了python正则实现计算器功能的具体代码，供大家参考，具体内容如下 # -*- coding: utf-8 -*-

# Author :Gogh

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

# @Email :361910002@qq.com

import re

def operator_update(formula):

# 对formula公式进行 去除空字符，更新运算符处理

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

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

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

return formula

def calc_muldiv(formula_list):

'''''

计算公式里面的乘除

: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):

'''''

计算列表数字的加减

:param operators: 运算符列表

:param num_list: 进行运算的数字列表

:return: 返回计算结果

'''

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):

'''''

把列表中这样的形式'2*' '-3*' '5/3*' '4/2'合并到一块

: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):

'''''

对括号最内层的formula公式进行计算

:param formula:

:return:

'''

formula = re.sub("[()]", "", formula) # 去除两边的()

formula = operator_update(formula)

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

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

if multiply_divide_list[0] == "": # multiply_divide_list列表第一个字符为空的话，表示一个数字为负号

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 '+' '-' 运算符 进行合并处理

multiply_divide_list = res[1]

plus_minus_list = calc_muldiv(multiply_divide_list) # 生成只进行加减运算的列表

res = calc_plumin(plus_minus_operator, plus_minus_list)

return res

def calculate(formula):

'''''计算程序主入口, 主要逻辑是先计算拓号里的值,算出来后再算乘除,再算加减'''

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结果:%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)

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持聚米学院。