Python Scientific calculator (calculator)

Description

The calculator is written primarily to practice regular expressions and Python basics: code comparison low!

Run process

Enter your calculation formula and the calculator will output the results to the screen (the steps will be printed here); Exit (Exit/quit)
Mycalc> 1-2 * ((60-30 + ( -40/5) * (9-2*5/3 + 7/3*99/4*2998 +10 * 568/14))-( -4*3)/(16-3*2)) 1-2* ((60-30+ ( -40/5) * ( 9-2*5/3+7/3*99/4*2998+10*568/14))-( -4*3)/(16-3*2))-----------steps [] [' -40/5 '] ( -40/5) Results: -8.0parenthesis_calc_ Result:1-2* ((60-30+-8.0* (9-2*5/3+7/3*99/4*2998+10*568/14))-( -4*3)/(16-3*2))-----------steps ['-', ' + ', ' + '] [' 9 ', ' 2*5 /3 ', ' 7/3*99/4*2998 ', ' 10*568/14 '] (9-2*5/3+7/3*99/4*2998+10*568/14) operation Result: 173545.88095238098parenthesis_calc_ Result:1-2* ((60-30-8.0*173545.88095238098)-( -4*3)/(16-3*2))-----------steps ['-', '-'] [' 60 ', ' 30 ', ' 8.0* 173545.88095238098 '] (60-30-8.0*173545.88095238098) operation results: -1388337.0476190478parenthesis_calc_result:1-2* (- 1388337.0476190478-( -4*3)/(16-3*2))-----------steps [] [' -4*3 '] ( -4*3) Results: -12.0parenthesis_calc_result:1-2* (- 1388337.0476190478--12.0/(16-3*2))-----------steps ['-'] [' 16 ', ' 3*2 '] (16-3*2) operation results: 10.0parenthesis_calc_result:1-2* ( -1388337.0476190478+12.0/10.0)-----------steps [' + '] ['-1388337.0476190478 ', ' 12.0/10.0 '] ( -1388337.0476190478+12.0/10.0) operation Result: -1388335.8476190479parenthesis_calc_result:1-2*-1388335.8476190479-----------Step ['-'] [' 1 ', ' 2*- 1388335.8476190479 ']1-2*-1388335.8476190479 operation results: 2776672.6952380957 The result of the final operation: 2776672.6952380957

　　

Specific code implementation

#/usr/bin/env python3# _*_ coding:utf-8 _*___author__ = ' Rianley cheng ' __blog__ = ' Https://www.cnblogs.com/rianley ' Left are too short, I use Python! Data normalization, regular splitting, combining operation printing operation expressions and Operation steps ' Import re,timedef math_legal (num): #判断输入公式是否合法, such as containing characters or Special characters, do special processing try:num = float (num) return True except (valueerror,typeerror) as Diag:passdef CA Lc_formula (Formula): #替换多余的加减操作 formula = Formula.replace ("+ +", "+") formula = Formula.replace ("+-", "-") Formul A = Formula.replace ("-+", "-") formula = Formula.replace ("--", "+") return formuladef Match_calc_formula (parenthesis Es_formula): #匹配加减操作符和加减表达式列表 # Remove all of the "-+" numbers in the parentheses expression, save as a list, such as ['-', ' + ', ' + '] # with the "+ +" sign as the delimiter, the multiplication expression in parentheses is taken out and saved in the form of a list, such as [' 9 ', ' 2*5/3 ', ' 7/3*99/4*2998 ', ' 10*568/14 '] Parenthesises_formula = Re.sub ("[()]", "", Parenthesises_formula) Plusminu S_operator_list = Re.findall ("[+ +]", parenthesises_formula) plusminus_expression_list = Re.split ("[+ +]", Parenthesises_formula) If Plusminus_expRession_list[0] = "": #圆括号表达式列表中, if the first element is empty, the first element is a negative number, then the "-" sign begins with the first "-" sign merged into the first element of the list Plusminus_expression_li ST[1] = plusminus_operator_list[0] + plusminus_expression_list[1] del plusminus_expression_list[0] del PLUSM        Inus_operator_list[0] for I, E in Enumerate (plusminus_expression_list): #处理成正确的结果: [' 1 *-2 ', ' 3 *-5 ', ' 6/-3 '] E = E.strip () if E.endswith ("*") or E.endswith ("/"): Try:plusminus_expression_list [i] = Plusminus_expression_list[i] + plusminus_operator_list[i] + plusminus_expression_list[i + 1] del Plus                Minus_expression_list[i + 1] del plusminus_operator_list[i] except Indexerror as Diag: Pass return plusminus_operator_list,plusminus_expression_listdef Matching_multiply_divide_operator (Plusminus_equa tions): #匹配乘除操作符和乘除表达式列表 operator_list = Re.findall ("[*/]", plusminus_equations) value_list = Re.split ("[*/]", plus Minus_equations) RetuRN operator_list,value_listdef Plus_minus_calc (plusminus_operator_list,plusminus_expression_list): #加减运算 " Add and subtract operations to an arithmetic formula, return the result of "Plusminus_result = None for I, E in Enumerate (plusminus_expression_list): match = Math_                     Legal (e) if match = = True:if Plusminus_result:if plusminus_operator_list[i-1] = = "+":                    Plusminus_result + = float (e) elif plusminus_operator_list[i-1] = = "-": Plusminus_result-= float (e) Else:plusminus_result = float (e) Else:prin            T ("\33[33;0m input formula contains non-numeric characters!\33[0m") print ("\33[33;0m attempt operation:%s\33[0m"% e) e = re.sub ("\d", "", e)                    If E = = "": E = 0 if plusminus_result:if plusminus_operator_list[i-1] = = "+": Plusminus_result + = float (e) elif plusminus_operator_list[i-1] = = "-": Plus          Minus_result-= float (e)  Else:try:plusminus_result = float (e) except ValueError as Diag: Print ("\33[33;1m Invalid input! \33[0m ") return plusminus_resultdef Multiply_divide_calc (multiply_divide_operator_list,multiply_divide_value_list ): #乘除运算 ' multiplication operation on the formula, return multiplication result ' Multiply_divide_result = None for I, Num in enumerate (multiply_divide_value_li ST): match = Math_legal (num) If match = = True:if Multiply_divide_result:if Multi PLY_DIVIDE_OPERATOR_LIST[I-1] = = "*": Multiply_divide_result *= float (num) elif Multip                    LY_DIVIDE_OPERATOR_LIST[I-1] = = "/": Try:multiply_divide_result/= float (num)                        Except Zerodivisionerror as Diag:multiply_divide_result = 0 Print ("\33[33;0m input formula has a divisor of 0, re-enter!")  \33[0m ") Else:multiply_divide_result = float (num)      Else:print ("\33[33;0m input formula has unrecognized content!\33[0m") print ("\33[33;0m try to calculate for you:%s\33[0m"% num) num = re.sub ("\d", "", num) if num = = "": num = 1 if multiply_divide_result:if MULTIPLY_DIVIDE_OPERATOR_LIST[I-1] = = "*": Multiply_divide_result *= float (num) elif m                ULTIPLY_DIVIDE_OPERATOR_LIST[I-1] = = "/": Multiply_divide_result/= float (num) Else:                    Try:multiply_divide_result = float (num) except ValueError as Diag: Print ("\33[33;1m Invalid input! \33[0m ") return multiply_divide_resultdef Calculating_priority_formulas (priority_formula): #计算圆括号表达式" "" "" "Plus Minus_operator_list, plusminus_expression_list = Match_calc_formula (priority_formula) print ("-----------") print ("\ 33[31;1m step \33[0m ") print (Plusminus_operator_list, plusminus_expression_list) for index, equations in enumerate (Plusminus_expression_list): If "*" in Equations or "/" in Equations: "" "" "" Multiply_divide_o Perator_list, multiply_divide_value_list = Matching_multiply_divide_operator (equations) Multiply_divide_result = Multiply_divide_calc (multiply_divide_operator_list, multiply_divide_value_list) #取出乘除表达式进行乘除运算 Plusminus_exp Ression_list[index] = Multiply_divide_result Plus_minus_result = Plus_minus_calc (Plusminus_operator_list, Plusminus_ Expression_list) #将乘除的结果进行加减运算 print ("%s operation result:%s"% (Priority_formula, Plus_minus_result)) return Plus_minus_resu Ltdef start_operation (Formula): "" "Operation Main program entrance, processing the input mathematical formula, matching the lowest-level parenthesis expression, and give multiplication function to calculate the return result, replace the parentheses expression" "" formula = Formula.rep  Lace ("", "") #去掉表达式多余的空格 formula = Calc_formula (Formula) #去掉表达式里重复的 "+-" print (Formula) Parenthesises_flag = True while Parenthesises_flag:formula = Calc_formula (Formula) Parenthesis_formula = Re.search (r "\ ([^ ()] ]+) \) ", formula) ifParenthesis_formula:parenthesis_formula = Parenthesis_formula.group () Parenthesis_calc_result = cal Culating_priority_formulas (parenthesis_formula) formula = Formula.replace (Parenthesis_formula, str (parenthesis_ Calc_result)) Print ("Parenthesis_calc_result:%s"% formula) Else:calc_result = Calculating_ Priority_formulas (Formula) Parenthesises_flag = False print ("Result of last operation: \33[31;1m%s\33[0m"% Calc_resu LT) def Mycalcmain (): prompt = "' Enter your calculation formula and the calculator will output the results to the screen (the steps will be printed here); Exit (Exit/quit) Example formula: 1-2 * ((60-30 + ( -40/5) * (9-2*5/3 + 7/3*99/4*2998 +10 * 568/14))-( -4*3)/(16-3*2)) ' Print (            prompt) While True:formula = input ("mycalc>"). Strip () if formula = = "Exit" or formula = = "Quit": Print (' Welcome to the next use, Welcome to the author Blog!            (Https://cnblogs.com/rianley) For more information please expect ') Time.sleep (3) exit ("Bye.bye ...") elif formula = = "":          Continue else:  Start_operation (Formula) If __name__ = = ' __main__ ': Mycalcmain () 

　　

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Python Scientific calculator (calculator)