The function home Plus implements the simple calculator

This implementation mainly uses the knowledge of the regular matching knowledge and functions to complete a calculator to achieve a simple subtraction calculation

Import re# multiplication Operation def numl_mod (args): Resurt = Re.compile (' (\d+\.? \d*) ([*/]) (\-?\d+\.? \d*) ') #正则匹配, assigns the matched result to Resurt while Resurt.search (args): #while循环判断直到算出最终结果 new_num = Resurt.search (args) n        Um = New_num.group () #取出原值赋给num num1 = float (new_num.group (1)) num2 = New_num.group (2) #取出来的是 */number, judged at if num3 = Float (New_num.group (3)) if num2 = = ' * ': result = NUM1 * num3# return * results elif num2 = '/': result = num1/num3# Returns/results of args = Args.replace (num, str (result), 1) #将计算的结果替换返回 return args# p Rint (Numl_mod ("10*2/5")) # #加减运算def Poor_add (args): Resurt = Re.compile (' (\-?\d+\.? \d*) ([-+]) (\-?\d+\.? \d*) ' while Resurt.search (args): New_num = resurt.search (args) num = New_num.group () Num1 = float            (New_num.group (1)) num2 = New_num.group (2) num3 = Float (New_num.group (3)) if num2 = = '-': result = num1-num3 elif num2 = = ' + ': result = Num1 + num3        args = Args.replace (num, str (result), 1) Return args# print (Poor_add ("3-5+6")) #检查判断去括号 # origin = "1-2* ((60-30+ ( -9-2-5-2*3-5/3-40*4/2-3/5+6*3) * ( -9-2-2*5/3+7/3*99/4*2998+10*568/14))-( -4*3)/(16-3*25)) "# origin = input (" Enter Number >>>>> ") #检测式子的合法性def check (args): flag = true# The default identity bit is true if Re.findall (" [A-za-z] ", args): #检查式子的合法性, Cannot contain uppercase and lowercase letters print ("error") flag = False return flag# detection Operation def format (args): #检测式子, replace with space/++/+-/--, etc., to return a new formula Sub NEW_ARGS1 = Args.replace ("+ +", "+") New_args2 = New_args1.replace ("+-", "-") New_args3 = New_args2.replace ("--") , "+") NEW_ARGS4 = New_args3.replace ("-+", "-") NEW_ARGS5 = New_args4.replace ("", "") NEW_ARGS6 = New_args5.repl Ace ("*+", "*") New_args = New_args6.replace ("/+", "/") return New_argsprint ("--------------") print ("Welcome to Computer") print ("-        -------------") #主代码块 # Executes the statement block while True:choice = input (" Select q/q "to Exit" y/y ") if choice = =" Q "or choice =" Q ": Print ("Thank you for your use") Break ORigin = input ("Enter number >>>>>") if check (origin): New_origin = Format (origin) while re . Search ("\ (", New_origin): #匹配如果有括号, execute the following code New_new_origin = Re.search ("\ ([^ ()]+\)", New_origin). Group () #匹配出最里面的括号里 The expression # Print (New_new_origin) s = Numl_mod (new_new_origin) # print (s) S1 = Poor_ Add (s) s2 = s1[1:-1] New_origin = New_origin.replace (New_new_origin, S2, 1) # Print (new_o Rigin) # Print (S2, type (s2)) # break Else: #括号执行完后执行的代码块 Resurt = Numl_mod (new_orig IN) # Print (Resurt, "Resurt") # print (resurt) New_resurt = Poor_add (resurt) # A2 = a2[1:-1] Print (New_resurt) #返回的最终结果, which is the final calculation we're going to get

　　

The function home Plus implements the simple calculator