计算器

1.计算器方法一

import re
MUL = 'd+(.d+)?[*/]-?d+(.d+)?'
ADD = '-?d+(.d+)?'

def fsdf(exp):
    exp = exp.replace('--','+')
    exp = exp.replace('+-', '-')
    exp = exp.replace('-+', '-')
    exp = exp.replace('++', '+')
    return exp

def mul_div(exp):
    lis = re.split('([*/])',exp)
    # print(len(lis))
    if lis[1] == '*':
        result = float(lis[0]) * float(lis[-1])
    else:
        result = float(lis[0]) / float(lis[-1])
    return result

def add_sub(exp):
    m = 0
    ret = re.finditer(ADD, exp)
    for ret1 in ret:
        result = ret1.group()
        m += float(result)
    return m

def first_(exp):
    exp = exp.replace(" ","")
    cp = re.compile('([^()]*)')
    try:
        while True:
            ret = re.search(cp,exp)  #m = '5+(6-1*(2-3/4))+(5-6/3)'  (2-3/4) (5-6/3)
            m = ret.group()
            while '*'in m or '/' in m:
                ret1= re.search(MUL,m)
                result = mul_div(ret1.group())
                m = re.sub(MUL,str(result),m,1)
            else:
                m = fsdf(m)
                result = add_sub(m)
                exp = re.sub(cp,str(result), exp, 1)
    except Exception as e:
        while '*' in exp or '/' in exp:
            ret1 = re.search(MUL, exp)
            result = mul_div(ret1.group())
            exp = re.sub(MUL, str(result), exp, 1)
        else:
            exp = fsdf(exp)
            result = add_sub(exp)
        return result

result = first_('5*-5+(6-1*(- 2-3/  -4))+(  5-6  /-3)')#
print(result)

2.计算器方法二

import re

MUL = 'd+(.d+)?[*/]-?d+(.d+)?'
ADD = '-?d+(.d+)?'

def symbol(exp):
    exp = exp.replace('--','+')
    exp = exp.replace('+-','-')
    exp = exp.replace('-+', '-')
    exp = exp.replace('++', '+')
    return exp

def mul_div(exp):
    """
    乘除法
    :param exp:
    :return:
    """
    if '*' in exp:
        a, b = exp.split('*')
        result = float(a) * float(b)
    else:
        a, b = exp.split('/')
        result = float(a) / float(b)
    return result

def add_sub(exp):
    m = 0
    ret = re.compile(ADD)
    while True:
        exp_add_sub = ret.finditer(exp)
        for i in exp_add_sub:
            m += float(i.group())
        exp = exp.replace(exp, str(m))
        return exp


def cal_mul_div(exp):
    ret = re.compile(MUL)
    while True:
        m = ret.search(exp)
        if m:
           exp_mul_div = m.group()
           result = mul_div(exp_mul_div)
           exp = exp.replace(exp_mul_div,str(result))
        else:break
    return exp

def all(exp):
    result = cal_mul_div(exp)
    result = symbol(result)
    result = add_sub(result)
    return result

def run(exp):   # m = '5+(6-1*(2-3/4))+(5-6/3)'
    exp = exp.replace(" ","")
    ret = re.compile("([^()]+)")
    while True:
        n = ret.search(exp)
        if n:
            m = n.group()
            result = all(m)
            exp = exp.replace(m,str(result))
        else:break
    result = all(exp)
    return result

exp = '1 - 2 * ( (60-30 +(-40/5) * (9-2*5/3 + 7 /3*99/4*2998 +10 * 568/14 )) - (-4*3)/ (16-3*2) )'
result = run(exp)
print(result)