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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:

技术分享
#!/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:

技术分享
****************** 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
View Code

 

Python学习之路-python基础课 (day6)