python写的计算器程序

模拟加减乘除，用正则和递归实现，效率有点低，主要目的是练习正则。

执行效果如下：

1 - 2 * ( (60-30 +(-40/5) * (9-2*5/3 + 7 /3*99/4*2998+10 * 568/14 )) - (-4*3)/ (16-3*2) )  #原始计算公式
1 - 2 * ( (60-30 +(-40/5) * (9-2*5/3 + 7 /3*99/4*2998+10 * 568/14 )) - (-4*3)/ (16-3*2) )  #原始计算公式
1-2*((60-30+-8.0*(9-2*5/3+7/3*99/4*2998+10*568/14))-(-4*3)/(16-3*2))  #提取（-40/5）进行计算，去除了所有的空白字符
1-2*((60-30+-8.0*173545.88095238098)-(-4*3)/(16-3*2))　　#提取（9-2*5/3+7/3*99/4*2998+10*568/14）进行计算
1-2*(-1388337.0476190478-(-4*3)/(16-3*2))　　#提取（60-30+-8.0*173545.88095238098）进行计算
1-2*(-1388337.0476190478--12.0/(16-3*2))　　#提取（-4*3）进行处理
1-2*(-1388337.0476190478--12.0/10.0)　　#提取（16-3*2）进行处理
1-2*-1388335.8476190479　　#提取（-1388337.0476190478--12.0/10.0）进行处理
2776672.6952380957　　#最终结果，与计算器结果执行一致

  1 #!/usr/bin/env python
  2 #-*- coding:utf-8 -*-
  3 # @Time    : 2017/11/6 15:37
  4 # @Author  : lichuan
  5 # @File    : calcu.py
  6 
  7 
  8 import re
  9 import time
 10 # s='3 * 10+9/3+2 * 6'
 11 # re.compile('[-+]')
 12 
 13 #做乘法除法
 14 def mul(strings):
 15     '''
 16     乘法加法
 17     :param s:
 18     :return:
 19     '''
 20     # print('this is add_del function')
 21     pattern=re.compile('\d+\.?\d*[\*\/]+[-+]?\d+\.?\d*')
 22     match=pattern.search(strings)
 23     if not match:
 24         return strings
 25     s=match.group()
 26     if '*' in s:
 27         value1=s.split('*')[0]
 28         value2=s.split('*')[1]
 29         value=float(value1)*float(value2)
 30     elif '/' in s:
 31         value1 = s.split('/')[0]
 32         value2 = s.split('/')[1]
 33         value = float(value1) / float(value2)
 34     new_s=pattern.sub(str(value),strings,count=1)
 35     # print(new_s)
 36     return mul(new_s)
 37 
 38 #做加法减法
 39 def add_del(strings):
 40     # print('this is add_del function')
 41     strings=clear(strings)
 42     pattern = re.compile('[-]?\d+\.?\d*\s*[-+]+\s*\d+\.?\d*')
 43     match = pattern.search(strings)
 44     if not match:
 45         return strings
 46     s=match.group()
 47     if '+' in s:
 48         value1 = s.split('+')[0]
 49         value2 = s.split('+')[1]
 50         value = float(value1) + float(value2)
 51         new_s = pattern.sub(str(value), strings, count=1)
 52         return add_del(new_s)
 53     elif '-' in s :
 54         if re.match('^-',s):
 55             value1 = s.split('-')[1]
 56             value2 = s.split('-')[2]
 57             value = -float(value1) - float(value2)
 58         else:
 59             value1 = s.split('-')[0]
 60             value2 = s.split('-')[1]
 61             value = float(value1) - float(value2)
 62     new_s = pattern.sub(str(value), strings, count=1)
 63     # print(new_s)
 64     return add_del(new_s)
 65 
 66 #提取括号内容进行操作
 67 def brackets(strings):
 68     # print('this is brackets function')
 69     print(strings)
 70     strings = re.sub('\s', '', strings)
 71     # strings=clear(strings)
 72     pattern = re.compile('\([-]?\d+\.?\d*\s*([-+*/]*\s*\d+\.?\d*\s*){1,}\)')
 73     match = pattern.search(strings)
 74     if not match:
 75         s=mul(strings)
 76         r=add_del(s)
 77         return r
 78     else:
 79         s=match.group()
 80         new_s=s.replace('(','')
 81         new_s=new_s.replace(')','')
 82         m_s=mul(new_s)
 83         a_s=add_del(m_s)
 84         # print(a_s)
 85         # print(strings)
 86         r=pattern.sub(a_s,strings,count=1)
 87         return brackets(r)
 88 
 89 #合并--、-+、+-、++等重复的运算符
 90 def clear(strings):
 91     # print('this is clear function')
 92     s=strings
 93     pattern_1 = re.compile('[-+]+[-+]+')
 94     m = pattern_1.search(strings)
 95     if not m:
 96         return strings
 97     else:
 98         strings=re.sub('--','+',s)
 99         strings=re.sub('-+','-',strings)
100         strings=re.sub('\+\+','+',strings)
101         strings=re.sub('\+\-','-',strings)
102         return clear(strings)
103 
104 
105 if __name__ == '__main__':
106     start=time.time()
107     s = '1 - 2 * ( (60-30 +(-40/5) * (9-2*5/3 + 7 /3*99/4*2998+10 * 568/14 )) - (-4*3)/ (16-3*2) )'
108     print(s)
109     b=brackets(s)
110     print(b)
111     end=time.time()