用函数写一个计算器(亲测完整版)

import re
def atom_cal(exp):
    if ‘*‘ in exp:
        a,b = exp.split(‘*‘)
        return str(float(a)*float(b))
    elif ‘/‘ in exp:
        a,b = exp.split(‘/‘)
        return str(float(a)/float(b))

def mul_div(exp):
    while True:
        ret = re.search(‘\d+(\.\d+)?[*/]-\d+(\.\d+)?‘,exp)
        if ret:
            atom_exp = ret.group()
            res = atom_cal(atom_exp)
            exp = exp.replace(atom_exp,res)
        else:
            return exp

def format_exp(exp):
    exp = exp.replace(‘--‘,‘+‘)
    exp = exp.replace(‘++‘,‘+‘)
    exp = exp.replace(‘+-‘,‘-‘)
    exp = exp.replace(‘-+‘,‘-‘)
    return exp

def add_sub(exp):
   ret = re.findall(‘[+-]?\d+(?:\.\d+)?‘,exp)
   exp_sum = 0
   for i in ret:
       exp_sum += float(i)
   return exp_sum

def cal(exp):
    exp = mul_div(exp)
    exp = format_exp(exp)
    exp_sum = add_sub(exp)
    return exp_sum

def main(exp):
    exp = exp.replace(‘ ‘,‘‘)
    while 1:
        ret = re.search(‘\([^()]+\)‘,exp)
        if ret:
            inner_bracket = res.group()
            res = str(cal(inner_bracket))
            exp = exp.replace(inner_bracket,res)
        else:break
    return cal(exp)

ret = main(s)
print(ret,type(ret))