计算器<代码>

  1 import re
  2 l_no = "-4.0*-4+((-1-8.0*2*-1)-(-9.456/1.57))/8+-8*7"
  3 true_tr = "-4.0*-4+((-1-8.0*2*-1)-(-9.456/1.57))/8+-8*7"
  4 trunswer = eval(true_tr)
  5 print(trunswer)
  6 
  7 l = re.sub(" +","",l_no)
  8 l_list = list(l)
  9 def check_w(formula):                     #  check函数
 10     formula=re.sub("--","+",formula)
 11     formula=re.sub("-\+|\+-","+",formula)
 12     a = re.findall("[a-z]|[A-Z]",formula)
 13     b = re.findall("\(\)",formula)
 14     if a or b:
 15         print("存在字母空括号")
 16         exit()
 17     return formula
 18 l_no = check_w(l_no)
 19 s = l_no
 20 def left_parenthesis(formula):         # find the left parenthesis  --
 21     a = re.search("\(", formula)
 22     if a == None:
 23         return None
 24     b = a.span()
 25     return b[1]
 26 def right_parenthesis(formula):          # find the right parenthesis --
 27     a = re.search("\)", formula)
 28     if a == None:
 29         return None
 30     b = a.span()
 31     return b[1]
 32 def code_muldiv(numcc):                # function for multiplication and division
 33     result = []                        # 这是一种算法 所有factor制成列表 所有mathematical symbol
 34     for i in numcc:                    # （-+或者*/）制成一个列表 之后利用列表有顺序来进行计算
 35         jishufuhao = 0                 # 正好适合8*-8这种形式
 36         jishushu = 1
 37         fuhao2 = []
 38         num = []
 39         fuhao2 = re.findall("\*|/",i)
 40         num = re.split("[*/]",i)             # 将所有因数（除数）整理成一个列表
 41         flag2 =True
 42         while flag2:
 43             if fuhao2[jishufuhao] == "*":
 44                 ga = float(num[jishushu-1]) * float(num[jishushu])
 45                 num[jishushu] = ga
 46                 jishushu+=1
 47                 jishufuhao+=1
 48             elif fuhao2[jishufuhao] == "/":
 49                 ha = float(num[jishushu - 1]) / float(num[jishushu])
 50                 num[jishushu] = ha
 51                 jishushu += 1
 52                 jishufuhao += 1
 53             if jishufuhao+1 > len(fuhao2):
 54                 flag2 = False
 55         result.append(num[jishushu-1])
 56     return result
 57 def code_addsub(numcc):       # function for addition and subtraction
 58     result = []
 59     for i in numcc:
 60         jishufuhao = 0
 61         jishushu = 1
 62         fuhao2 = []
 63         num = []
 64         i = re.sub("--","+",i)
 65         i = re.sub("\+-|-\+","-",i)
 66         i = re.sub("^\+","",i)
 67         a = re.findall("^-\d+\.?\d*",i)    ### 如果formula为 -9+8 ，这个函数的功能
 68         if a == []:                        ### 就是将其转换为  0+8-9 这样便将minus
 69             pass                           ### 转化为无符号式子
 70         else:                              ###
 71             i = re.sub(a[0],"0",i,1)       ###
 72             i = "".join([i,a[0]])          ###
 73         fuhao2 = re.findall("\+|-",i)
 74         num = re.split("[+-]",i)
 75         if fuhao2 ==[]:
 76             return numcc
 77         flag2 = True
 78         while flag2:
 79             if fuhao2[jishufuhao] == "+":
 80                 ga = float(num[jishushu-1]) + float(num[jishushu])
 81                 num[jishushu] = ga
 82                 jishushu+=1
 83                 jishufuhao+=1
 84             elif fuhao2[jishufuhao] == "-":
 85                 ha = float(num[jishushu - 1]) - float(num[jishushu])
 86                 num[jishushu] = ha
 87                 jishushu += 1
 88                 jishufuhao += 1
 89             if jishufuhao+1 > len(fuhao2):
 90                 flag2 = False
 91         result.append(num[jishushu-1])
 92     return result
 93 def exchange_l(formula):           # for calculating mul div
 94     flag4 = True
 95     while flag4:
 96         need_md = re.findall("\d+\.?\d*[*/]-?\d+\.?\d*",formula)
 97         if need_md == []:
 98             break
 99         e = need_md
100         k = code_muldiv(e)
101         out_s = formula.replace(str(need_md[0]),str(k[0]))
102         formula =out_s
103     return formula
104 flag2 = True
105 while flag2:
106     flag = True
107     a = 0
108     y_y=right_parenthesis(s)
109     if y_y == None:                       # 判断 没有括号时，直接计算
110         formula_jj = exchange_l(l)
111         final_result = code_addsub([formula_jj])
112         l = l.replace(l, str(final_result[0]), 1)
113         s = l
114         print("result:",s)
115         break
116     else:
117         y = right_parenthesis(s) - 1
118     while flag:                              # 多次寻找左括号 并且切片后再寻找
119         position_psis = left_parenthesis(s)
120         if position_psis == None:
121             position_psis = 0
122             break
123         s= s[position_psis:]             # 将找到的左括号后面的字符串切片
124         a += position_psis               # 记录下序列号
125         if a > y:                        # 若是左括号序列号比右括号大 则停止寻找
126             flag = False
127     a = a - position_psis
128     need_l = l[a:y]                      # 需要处理的括号内容
129     ex_input = l[a - 1:y + 1]
130     need_l =str(need_l)   # 3+2-3
131     formula_jj = exchange_l(need_l)      # 进行乘除处理
132     final_result = code_addsub([formula_jj]) # 进行加减处理
133     l = l.replace(ex_input, str(final_result[0]), 1) # 用结果替换掉字符串
134     s = l                                            # 赋值再次循环用