开发一个简单的python计算器

要求：

1. 实现加减乘除及拓号优先级解析
2. 用户输入 1 - 2 * ( (60-30 +(-40/5) * (9-2*5/3 + 7 /3*99/4*2998 +10 * 568/14 )) - (-4*3)/ (16-3*2) )等类似公式后，必须自己解析里面的(),+,-,*,/符号和公式(不能调用eval等类似功能偷懒实现)，运算后得出结果，结果必须与真实的计算器所得出的结果一致

  1 import re
  2
  3 def main():
  4
  5     a = ‘‘.join(input(‘请输入需要计算的算式‘).split())
  6
  7     while True:
  8         if ‘(‘ in a:
  9             ct = re.search(r‘\(([^()]+)\)‘, a)
 10             if ct is not None:
 11                 b = ct.groups()[0]
 12                 c = count(b)
 13                 a = re.sub(r‘\(([^()]+)\)‘, str(c), a, 1)
 14         else:
 15             c = count(a)
 16             print(c)
 17             break
 18
 19 def add_min(a):
 20     ‘‘‘
 21     计算加减法
 22     :param:
 23     :return:
 24     ‘‘‘
 25
 26     if ‘--‘ in a:
 27         a = a.replace(‘--‘, ‘+‘)
 28
 29     c = re.findall(r‘-?\d+\.?\d*‘, a)
 30     ls = []
 31     for i in c:
 32         ls.append(float(i))
 33     rest = sum(ls)
 34     return rest
 35
 36
 37 def mul(a):
 38     ‘‘‘
 39     计算剩数
 40     :param ct:
 41     :return:
 42     ‘‘‘
 43
 44
 45     b = re.search(r‘\d+\.?\d*(\*-?\d+\.?\d*)+‘, a)
 46     if b is not None:
 47         b = b.group()
 48         rest = 1
 49         c = re.findall(r‘-?\d+\.?\d*‘, b)
 50         ls =[]
 51         for item in c:
 52             ls.append(float(item))
 53         for i1 in range(len(ls)):
 54             rest = rest * ls[i1]
 55         a = re.sub(r‘\d+\.?\d*(\*-?\d+\.?\d*)+‘, str(rest), a, 1)
 56         return a
 57
 58
 59
 60 def div(a):
 61     ‘‘‘
 62     计算出发
 63     :param a:
 64     :return:
 65     ‘‘‘
 66
 67     b = re.search(r‘\d+\.?\d*(\/-?\d+\.?\d*)+‘, a)
 68     if b is not None:
 69         b = b.group()
 70         c = re.findall(r‘-?\d+\.?\d*‘, b)
 71         ls =[]
 72         for i in c:
 73             ls.append(float(i))
 74         rest = ls[0]
 75         for i1 in range(1,len(ls)):
 76             rest = rest / ls[i1]
 77         a = re.sub(r‘\d+\.?\d*(\/-?\d+\.?\d*)+‘, str(rest), a, 1)
 78         return a
 79
 80
 81 def count(b):
 82     ‘‘‘
 83     计算结果
 84     :return:
 85     ‘‘‘
 86     while True:
 87         if ‘*‘ in b:
 88             c = b.split(‘*‘)
 89             if ‘/‘ in c[0]:
 90                 b = div(b)
 91             else:
 92                 b = mul(b)
 93         elif ‘/‘ in b:
 94             b = div(b)
 95
 96         elif ‘+‘ or ‘-‘ in b:
 97             b = add_min(b)
 98             return b
 99         else:
100             return b
101
102
103
104
105 main()