计算器

Posted 2020-09-22

import re
def init_compute(compute):
    #输出计算式列表
    compute_a = re.sub(‘ ‘,‘‘, compute)
    compute_l = []
    compute_list = []
    for i in re.split(‘(\-\d+\.*\d*)‘,compute_a):
        if i:
            compute_l.append(i)
    while True:
        exp = compute_l.pop(0)
        if len(compute_list) == 0 and re.search(‘^\-\d+\.*\d*$‘,exp):
            compute_list.append(exp)
            continue
        if len(compute_list) != 0 :
            if re.search(‘([\+\-\*\/\(]$)‘,compute_list[-1]):
                compute_list.append(exp)
                continue
        for i in re.split(‘([\+\-\*\/\(\)])‘,exp):
            if i:
                compute_list.append(i)
        if len(compute_l) == 0:
            break
    print(compute_list)
    return compute_list

def is_symbol(i):
    #判断是否为运算符
    res = False
    symbol = [‘+‘,‘-‘,‘*‘,‘/‘,‘(‘,‘)‘]
    if i in symbol:
        res = True
    return res

def judgement(old_i,new_i):
    #判断运算符优先级
    level1 = [‘+‘,‘-‘]
    level2 = [‘*‘,‘/‘]
    level3 = [‘(‘]
    level4 = [‘)‘]
    if old_i in level1:
        if new_i in level2 or new_i in level3:
            return ‘<‘
        else:
            return ‘>‘
    elif old_i in level2:
        if new_i in level3:
            return ‘<‘
        else:
            return ‘>‘
    elif old_i in level3:
        if new_i in level4:
            return ‘=‘
        else:
            return ‘<‘


def calculate(num1,symbol,num2):
    #对数字进行计算
    res=0
    if symbol == ‘+‘:
        res = num1+num2
    elif symbol == ‘-‘:
        res = num1-num2
    elif symbol == ‘*‘:
        res = num1*num2
    elif symbol == ‘/‘:
        res = num1/num2
    return res

def main(compute_1):
    #主函数
    numbers = []
    symbols = []
    for i in compute_1:
        ret = is_symbol(i)
        if ret == False :  #判断列表元素是否为数字
            i = float(i)
            numbers.append(i)
        else:
            while True:
                if len(symbols) == 0:
                    symbols.append(i)
                    break
                res = judgement(symbols[-1],i)
                if res == ‘<‘:
                    symbols.append(i)
                    break
                elif res == ‘=‘:
                    symbols.pop()
                    break
                elif res == ‘>‘:
                    symbol = symbols.pop()
                    num2 = numbers.pop()
                    num1 = numbers.pop()
                    numbers.append(calculate(num1, symbol, num2))

    else:
        while True:
            if len(numbers) == 1:
                break
            symbol = symbols.pop()
            num2 = numbers.pop()
            num1 = numbers.pop()
            numbers.append(calculate(num1, symbol, num2))
    return numbers
def run():
    print(‘示例:-1 - 2 *((-60+30+(-40/5)*(-9-2*-5/30-7/3*99/4*2998+10/-568/14))-(-4*-3)/(16-3*2))+3‘)
    #-1 - 2 * (-2 + 3)
    compute = input(‘请输入您要计算的公式:‘)
    compute_1 = init_compute(compute)
    l = main(compute_1)
    print(‘计算结果：%s‘%l)

if __name__ == ‘__main__‘:
    run()