s12-day04-work01 简单计算器功能实现

代码：

 #!/usr/local/env python3
 '''
 Author:@南非波波
 Blog:http://www.cnblogs.com/songqingbo/
 E-mail:qingbo.song@gmail.com
 '''

 import time,sys
 import module

 if __name__ == "__main__":
     while True:
         count = 0
         if count < 3:
             print('''
             请输入一个计算公式，类似下面格式：
             =========================================================================================
             1 - 2 * ( (60-30 +(-40/5) * (9-2*5/3 + 7 /3*99/4*2998 +10 * 568/14 )) - (-4*3)/ (16-3*2) )
             =========================================================================================
             系统默认匹配所有的数字、(、)、+、-、/、*、.
                                                                                 计算器程序研发@南非波波
             ''')
             expression = input("请输入:").strip()  #或取用户输入的表达式字符串，并去除左右的空格
             # expression = "1 - 2 * ( (60-30 +(-40/5) * (9-2*5/3 + 7 /3*99/4*2998 +10 * 568/14 )) - (-4*3)/ (16-3*2) )"
             expression = expression.replace(' ','') #去除字符串中间的空格，使用replace进行空字符串替换空格
             if module.num_operator(expression): #成功匹配正确表达式
                 # print(expression)
                 result = module.recursion_bracket(expression) #将处理后没有括号的表达式赋值给expression
                 print(result)
                 break
             else:
                 count += 1
                 print("你输入的表达式格式不正确!")
                 time.sleep(1)
                 continue
         else:
             print("你的输入错误次数已达三次,计算器将自动退出!感谢你的使用!")
             time.sleep(1)
             sys.exit(3)

index.py

 #!/usr/local/env python3
 '''
 Author:@南非波波
 Blog:http://www.cnblogs.com/songqingbo/
 E-mail:qingbo.song@gmail.com
 '''

 import re

 #匹配一个表达式中的数字和运算符，如果匹配，返回expression，否则返回None
 def num_operator(expression):
     match_list = re.findall("[0-9]|\(|\)|\+|\-|\*|\/|.",expression)
     if len(expression) == len(match_list):
         return True

 #特殊字符处理
 def charmap(expression):
     flag = True
     while flag:
         if expression.__contains__("++") or expression.__contains__("+-") or expression.__contains__("-+") or expression.__contains__("--"):
             # match_str = re.search("\d+\.*\d*(\+\-){1}\d+\.*\d*",expression).group()
             expression = expression.replace('+-','-')
             expression = expression.replace('++','+')
             expression = expression.replace('-+','-')
             expression = expression.replace('--','+')
         else:
             flag = False
     return expression
 #操作加减
 def compute_add_sub(expression):
     '''
     expression表达式传进来的形式是(5+1-4)，左右成一对括号。所以这里需要将括号去掉
     '''
     expression = expression.lstrip('(').rstrip(')') #去除表达式左右的括号
     match_test = re.search("\d+\.*\d*[\+\-]{1}\d+\.*\d*",expression)
     if not match_test:
         return expression
     else:
         match_str = match_test.group()
         if len(match_str.split('+')) > 1:
             num1,num2 = match_str.split("+")
             result = float(num1) + float(num2)
         else:
             num1,num2 = match_str.split("-")
             result = float(num1) - float(num2)
         exp_join = expression.split(match_str)
         expression = "%s%s%s" % (exp_join[0],result,exp_join[1])
     return compute_add_sub(expression)

 #操作乘除
 def compute_mul_div(expression):
     '''
     expression表达式传进来的形式是(9-2*5/3+7/3*99/4*2998+10*568/14)，左右成一对的括号。所以这里就需要将括号去掉然后递归处理乘除
     '''
     expression = expression.lstrip('(').rstrip(')') #去除表达式左右的括号
     match_test = re.search("\d+\.*\d*[\*\/]+[\+\-]?\d+\.*\d*",expression)
     if not match_test: #判断是否能够匹配到* 或者 /。
         return expression
     else:
         match_str = match_test.group() #获取到匹配的运算式，比如5/3，2*5
         if len(match_str.split("/")) > 1: #计算除法
             num1,num2 = match_str.split("/")
             result = float(num1) / float(num2)
         else: #计算乘法 len(match_str.split("*")) > 1
             num1,num2 = match_str.split("*")
             result = float(num1) * float(num2)
         exp_join = expression.split(match_str)
         expression = "%s%s%s" % (exp_join[0],result,exp_join[1])
         compute_mul_div(expression)  #递归处理
     return compute_mul_div(expression)

 #处理优先级的执行
 def compute_pri(expression):
     expression = compute_mul_div(expression) #处理乘除
     expression = charmap(expression) #处理特殊字符
     expression = compute_add_sub(expression)  #处理加减
     return expression #返回一个值

 #递归处理括号
 def recursion_bracket(expression):
     match_list = re.findall("\(|\)",expression) #匹配括号,如果存在递归处理
     if not match_list:
         # print(expression)
         return compute_pri(expression)
     else:
         match_str = re.search("\([^()]*\)",expression) #匹配第一次出现的括号对
         if match_str:
             match_str = match_str.group()
             # print("match_str:",match_str)
             tmp = compute_pri(match_str)
             expression = "%s%s%s" % (expression.split(match_str)[0],tmp,expression.split(match_str)[1]) #字符串拼接
             # print("expression:",expression)
     return recursion_bracket(expression) #递归处理括号

 # expression = "(9-2*5/3+7/3*99/4*2998+10*568/14)"
 # res = compute_pri(expression)
 # print(res)
 #递归处理括号
 # def recursion_bracket(expression):
 #     match_list = re.findall("\(|\)",expression) #匹配括号,如果存在递归处理
 #     if match_list:
 #         tmp_list = [] #定义一个列表，存储左括号(
 #         res = ''
 #         for i in range(0, len(expression)):
 #             if expression[i] == "(":
 #                 tmp_list.append(i) #获取括号出现的索引值列表
 #                 print("tmp_list:",tmp_list)
 #                 continue
 #             if expression[i] == ")" and tmp_list:
 #                 ts = expression[tmp_list[-1]: i+1]
 #                 if len(ts) > len(res):
 #                     # ts = compute_mul_div(ts)
 #                     # print(ts)
 #                     # ts = charmap(ts)
 #                     # ts = compute_add_sub(ts)
 #                     res = ts
 #                     print('i:%s,ts:%s' % (i,ts))
 #                 tmp_list.pop()
 #                 print(tmp_list)
 #         print("res:",res)
 #         # return recursion_bracket(res)
 #
 #     else: #匹配括号失败，返回表达式,做后续处理
 #         expression = compute_mul_div(expression)
 #         expression = charmap(expression)
 #         expression = compute_add_sub(expression)

module.py

github代码更新地址：https://github.com/swht/projects/tree/master/day04/计算器