Python学习之路-python基础课 (day6)

 

作业：

开发一个简单的python计算器

1. 实现加减乘除及拓号优先级解析
2. 用户输入 1 - 2 * ( (60-30 +(-40/5) * (9-2*5/3 + 7 /3*99/4*2998 +10 * 568/14 )) - (-4*3)/ (16-3*2) )等类似公式后，必须自己解析里面的(),+,-,*,/符号和公式(不能调用eval等类似功能偷懒实现)，运算后得出结果，结果必须与真实的计算器所得出的结果一致

计算器源码：

#!/usr/bin/env python
# _*_ coding:utf-8 _*_
# Author: Mo

import re

def compute_multipy_divide(arg):
    value = arg[0]
    mch = re.search(\'\d+\.*\d*[\*\/]+[\+\-]?\d+\.*\d*\',value)
    if not mch:
        return
    content = re.search(\'\d+\.*\d*[\*\/]+[\+\-]?\d+\.*\d*\',value).group()
    if len(content.split(\'*\')) > 1:
        v1,v2 = content.split(\'*\')
        get_value = float(v1) * float(v2)
    else:
        v1,v2 = content.split(\'/\')
        get_value = float(v1) / float(v2)
    left,right = re.split(\'\d+\.*\d*[\*\/]+[\+\-]?\d+\.*\d*\',value,1)
    new_value = \'%s%s%s\' %(left,get_value,right)
    arg[0] = new_value
    compute_multipy_divide(arg)

def compute_add_substract(arg):
    while True:
        if \'--\' in arg[0] or \'++\' in arg[0] or \'-+\' in arg[0] or \'+-\' in arg[0]:
            arg[0] = arg[0].replace(\'--\',\'+\')
            arg[0] = arg[0].replace(\'++\',\'+\')
            arg[0] = arg[0].replace(\'-+\',\'-\')
            arg[0] = arg[0].replace(\'+-\',\'-\')
        else:
            break
    if arg[0].startswith(\'-\'):
        arg[1] += 1
        arg[0] = arg[0].replace(\'-\',\'&\')
        arg[0] = arg[0].replace(\'+\',\'-\')
        arg[0] = arg[0].replace(\'&\',\'+\')
        arg[0] = arg[0][1:]
    value = arg[0]
    mch = re.search(\'\d+\.*\d*[\+\-]{1}\d+\.*\d*\',value)
    if not mch:
        return
    content = re.search(\'\d+\.*\d*[\+\-]{1}\d+\.*\d*\',value).group()
    if len(content.split(\'+\')) >1:
        v1,v2 = content.split(\'+\')
        get_value = float(v1) + float(v2)
    else:
        v1,v2 = content.split(\'-\')
        get_value = float(v1) - float(v2)
    left,right = re.split(\'\d+\.*\d*[\+\-]{1}\d+\.*\d*\',str(value),1)
    new_value = \'%s%s%s\' %(left,get_value,right)
    arg[0] = new_value
    compute_add_substract(arg)

def compute(expression):
    inp = [expression,0]
    compute_multipy_divide(inp)
    compute_add_substract(inp)
    count = divmod(inp[1],2)
    result = float(inp[0])
    if count[1] == 1:
        result = result * (-1)
    return result

def excute(expression):
    if not re.search(\'\(([\+\-\*\/]*\d+\.*\d*){2,}\)\',expression):
        result = compute(expression)
        return result
    content = re.search(\'\(([\+\-\*\/]*\d+\.*\d*){2,}\)\',expression).group()
    new_content = content[1:len(content)-1]
    new_list = re.split(\'\(([\+\-\*\/]*\d+\.*\d*){2,}\)\',expression,1)
    print(\'计算前：\',expression)
    left = new_list[0]
    right = new_list[2]
    final = compute(new_content)
    print(\'计算：%s=%s\' % (new_content, final))
    new_expression = \'%s%s%s\' %(left,final,right)
    print(\'计算后：\', new_expression)
    print(\'上次计算结束\'.center(50,\'*\'))
    return excute(new_expression)

def run():
    while True:
        print(\' Oldboy Calc \'.center(50, \'*\'))
        str_input = input(\'(quit=q)>>:\').strip()
        if str_input == \'q\': exit()
        if len(str_input) == 0 : continue
        if len(str_input) >0 :
            no_space_str = re.sub(\'\s*\',\'\',str_input)
        final = excute(no_space_str)
        print(final)

if __name__ == \'__main__\':
    run()

View Code

 

计算结果：

****************** Oldboy Calc *******************
(quit=q)>>:1 - 2 * ( (60-30 +(-40/5) * (9-2*5/3 + 7 /3*99/4*2998 +10 * 568/14 )) - (-4*3)/ (16-3*2) )
计算前： 1-2*((60-30+(-40/5)*(9-2*5/3+7/3*99/4*2998+10*568/14))-(-4*3)/(16-3*2))
计算：-40/5=-8.0
计算后： 1-2*((60-30+-8.0*(9-2*5/3+7/3*99/4*2998+10*568/14))-(-4*3)/(16-3*2))
**********************上次计算结束**********************
计算前： 1-2*((60-30+-8.0*(9-2*5/3+7/3*99/4*2998+10*568/14))-(-4*3)/(16-3*2))
计算：9-2*5/3+7/3*99/4*2998+10*568/14=173545.88095238098
计算后： 1-2*((60-30+-8.0*173545.88095238098)-(-4*3)/(16-3*2))
**********************上次计算结束**********************
计算前： 1-2*((60-30+-8.0*173545.88095238098)-(-4*3)/(16-3*2))
计算：60-30+-8.0*173545.88095238098=-1388337.0476190478
计算后： 1-2*(-1388337.0476190478-(-4*3)/(16-3*2))
**********************上次计算结束**********************
计算前： 1-2*(-1388337.0476190478-(-4*3)/(16-3*2))
计算：-4*3=-12.0
计算后： 1-2*(-1388337.0476190478--12.0/(16-3*2))
**********************上次计算结束**********************
计算前： 1-2*(-1388337.0476190478--12.0/(16-3*2))
计算：16-3*2=10.0
计算后： 1-2*(-1388337.0476190478--12.0/10.0)
**********************上次计算结束**********************
计算前： 1-2*(-1388337.0476190478--12.0/10.0)
计算：-1388337.0476190478--12.0/10.0=-1388335.8476190479
计算后： 1-2*-1388335.8476190479
**********************上次计算结束**********************
2776672.6952380957
****************** Oldboy Calc *******************
(quit=q)>>:q

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