Python科学计算器（计算器），,说明该计算器主要是为

Python科学计算器（计算器），,说明该计算器主要是为

说明

该计算器主要是为了练习正则表达式以及python基础所写：代码比较low！

运行过程

请输入你的计算公式, 计算器会将计算结果输出到屏幕上(此处会打印步骤); 退出（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))-----------步骤[] [‘-40/5‘](-40/5) 运算结果: -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))-----------步骤[‘-‘, ‘+‘, ‘+‘] [‘9‘, ‘2*5/3‘, ‘7/3*99/4*2998‘, ‘10*568/14‘](9-2*5/3+7/3*99/4*2998+10*568/14) 运算结果: 173545.88095238098parenthesis_calc_result: 1-2*((60-30-8.0*173545.88095238098)-(-4*3)/(16-3*2))-----------步骤[‘-‘, ‘-‘] [‘60‘, ‘30‘, ‘8.0*173545.88095238098‘](60-30-8.0*173545.88095238098) 运算结果: -1388337.0476190478parenthesis_calc_result: 1-2*(-1388337.0476190478-(-4*3)/(16-3*2))-----------步骤[] [‘-4*3‘](-4*3) 运算结果: -12.0parenthesis_calc_result: 1-2*(-1388337.0476190478--12.0/(16-3*2))-----------步骤[‘-‘] [‘16‘, ‘3*2‘](16-3*2) 运算结果: 10.0parenthesis_calc_result: 1-2*(-1388337.0476190478+12.0/10.0)-----------步骤[‘+‘] [‘-1388337.0476190478‘, ‘12.0/10.0‘](-1388337.0476190478+12.0/10.0) 运算结果: -1388335.8476190479parenthesis_calc_result: 1-2*-1388335.8476190479-----------步骤[‘-‘] [‘1‘, ‘2*-1388335.8476190479‘]1-2*-1388335.8476190479 运算结果: 2776672.6952380957最后的运算结果: 2776672.6952380957

具体代码实现

#/usr/bin/env python3# _*_ coding: utf-8 _*___author__ = ‘rianley cheng‘__blog__ =‘https://www.cnblogs.com/rianley‘‘‘‘left is too short , I use python !数据规范化， 正则拆分，结合运算  打印运算表达式及运算步骤‘‘‘import re,timedef math_legal(num):   #判断输入公式是否合法，如包含字符或者特殊字符，做特殊处理    try:        num = float(num)        return True    except (ValueError,TypeError) as diag:        passdef calc_formula(formula):  #替换多余的加减操作    formula = formula.replace("++", "+")    formula = formula.replace("+-", "-")    formula = formula.replace("-+", "-")    formula = formula.replace("--", "+")    return formuladef match_calc_formula(parenthesises_formula):  #匹配加减操作符和加减表达式列表    # 取出圆括号表达式中所有的"+-"号，保存为列表形式，如[‘-‘, ‘+‘, ‘+‘]    # 用"+-"号作为分隔符，将圆括号中的乘除表达式取出，保存为列表形式，如[‘9‘, ‘2*5/3‘, ‘7/3*99/4*2998‘, ‘10*568/14‘]    parenthesises_formula = re.sub("[()]", "", parenthesises_formula)    plusminus_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，如果第一个元素为空，则表明第一个元素为一个负数，则"-"号开头，将第一个"-"号合并到列表第一个元素        plusminus_expression_list[1] = plusminus_operator_list[0] + plusminus_expression_list[1]        del plusminus_expression_list[0]        del plusminus_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 plusminus_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_equations):  #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("[*/]", plusminus_equations)    return operator_list,value_listdef plus_minus_calc(plusminus_operator_list,plusminus_expression_list):  #加减运算    ‘‘‘对运算公式进行加减运算，返回加减结果‘‘‘    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:            print("\33[33;0m输入的公式中包含非数字字符!\33[0m")            print("\33[33;0m尝试运算: %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] == "-":                    plusminus_result -= float(e)            else:                try:                    plusminus_result = float(e)                except ValueError as diag:                    print("\33[33;1m无效输入！\33[0m")    return plusminus_resultdef multiply_divide_calc(multiply_divide_operator_list,multiply_divide_value_list):  #乘除运算    ‘‘‘对运算公式进行乘除运算，返回乘除结果‘‘‘    multiply_divide_result = None    for i, num in enumerate(multiply_divide_value_list):        match = math_legal(num)        if match == True:            if multiply_divide_result:                if multiply_divide_operator_list[i - 1] == "*":                    multiply_divide_result *= float(num)                elif multiply_divide_operator_list[i - 1] == "/":                    try:                       multiply_divide_result /= float(num)                    except ZeroDivisionError as diag:                        multiply_divide_result = 0                        print("\33[33;0m输入的公式中存在除数为0，重新输入！\33[0m")            else:                 multiply_divide_result = float(num)        else:            print("\33[33;0m输入的公式中存在无法识别的内容!\33[0m")            print("\33[33;0m尝试为您运算: %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 multiply_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无效输入！\33[0m")    return multiply_divide_resultdef calculating_priority_formulas(priority_formula):  #计算圆括号表达式    """"""    plusminus_operator_list, plusminus_expression_list = match_calc_formula(priority_formula)    print("-----------")    print("\33[31;1m步骤\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_operator_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_expression_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 运算结果: %s" % (priority_formula, plus_minus_result))    return plus_minus_resultdef start_operation(formula):    """ 运算主程序入口，对输入的数学公式进行处理，匹配最底层圆括号表达式，并交给乘除函数计算返回结果，替换圆括号表达式"""    formula = formula.replace(" ", "")    #去掉表达式多余的空格    formula = calc_formula(formula)  #去掉表达式里重复的"+-"号    print(formula)    parenthesises_flag = True    while parenthesises_flag:        formula = calc_formula(formula)        parenthesis_formula = re.search(r"\(([^()]+)\)", formula)        if parenthesis_formula:            parenthesis_formula = parenthesis_formula.group()            parenthesis_calc_result = calculating_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("最后的运算结果: \33[31;1m%s\33[0m" % calc_result)def myCalcMain():    prompt = ‘‘‘请输入你的计算公式, 计算器会将计算结果输出到屏幕上(此处会打印步骤); 退出（exit/quit）示例公式: 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(‘欢迎下次使用，欢迎关注作者博客！（https://cnblogs.com/rianley）更多资讯敬请期待‘)            time.sleep(3)            exit("Bye.Bye...")        elif formula == "":            continue        else:            start_operation(formula)if __name__ == ‘__main__‘:    myCalcMain()

结言

努力成为想要成为的人，就算最后失败了！也没关系，因为失败比遗憾可怕的多！

Python科学计算器（计算器）