函数加正则实现简单计算器

import re

#乘除运算
def numl_mod(args):
    resurt  = re.compile(‘(\d+\.?\d*)([*/])(\-?\d+\.?\d*)‘)#正则匹配,将匹配出来的结果赋给resurt
    while resurt.search(args):#while循环判断直到算出最终结果
        new_num = resurt.search(args)
        num = 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 * / 号，在if 处进行判断
        num3 = float(new_num.group(3))

        if num2 == ‘*‘:
            result = num1 * num3#返回 * 的结果
        elif num2 == ‘/‘:
            result = num1 / num3#返回 / 的结果
        args = args.replace(num, str(result), 1)#将计算的结果替换返回
    return args
# print(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#默认标识位为真
    if re.findall("[a-zA-Z]",args):#检查式子的合法性，不能含有大小写字母
        print("error")
        flag = False
    return flag

#检测运算
def format(args):#检测式子，将 含有空格/++/+-/--等进行替换，返回一个新的式子
    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.replace("*+","*")
    new_args = new_args6.replace("/+","/")
    return new_args

print("--------------")
print("欢迎使用计算机")
print("--------------")
#主代码块
#执行语句块
while True:
    choice = input("请选择 q/Q【退出】 y/Y 【执行】")
    if choice == "q" or choice == "Q":
        print("谢谢您的使用")
        break
    origin = input("Enter number >>>>>")
    if check(origin):
        new_origin = format(origin)
        while re.search("\(",new_origin):#匹配如果有括号，执行下面代码
            new_new_origin = re.search("\([^()]+\)",new_origin).group()#匹配出最里面的括号里的式子
            # 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_origin)
            # print(s2, type(s2))
            # break
        else:#括号执行完后执行的代码块
            resurt = numl_mod(new_origin)
            # print(resurt, "resurt")
            # print(resurt)
            new_resurt = poor_add(resurt)
            # a2 = a2[1:-1]
            print(new_resurt)#返回的最终结果，也就是我们要得到的最终计算结果