7_python之路之python计算器

7_python之路之python计算器

1.程序说明：Readme.cmd

1.程序文件及说明：

calculator.py

2.python版本：python-3.5.3

3.程序使用：python calculator.py "1 - 2 * ( (60-30 +(-40/5) * (9-2*5/3 + 7 /3*99/4*2998 +10 * 568/14 )) - (-4*3)/ (16-3*2) )"

    【使用双引号引住需要运算的内容】

4.程序功能解析：

    计算器

5.程序执行结果：请亲自动手执行或者查看我的博客

6.程序博客地址：http://www.cnblogs.com/chenjw-note/p/8523839.html

2.程序代码：calculator.py

#!/usr/bin/env python

# _*_ coding: utf-8 _*_

# author：chenjianwen

# email：[email protected]

import re

import sys

##计算乘除法

def compute_mutiply_and_dividend(formula):

    operators = re.findall(r'[*/]',formula)

    calc_list = re.split('[*/]',formula)

    calc_res =  None

    for index,i in enumerate(calc_list):

        if calc_res:

            if operators[index - 1] == "*":

                calc_res *= float(i)

            elif operators[index - 1] == "/":

                calc_res /= float(i)

        else:

            calc_res = float(i)

    return calc_res

##计算加减

def compute_add_and_subt(formula):

    operators = re.findall(r'[+-]',formula)

    calc_list = re.split(r'[+-]',formula)

    calc_res =  None

    for index,i in enumerate(calc_list):

        if calc_res:

            if operators[index - 1] == "+":

                calc_res += float(i)

            elif operators[index - 1] == "-":

                calc_res -= float(i)

        else:

            calc_res = float(i)

    return calc_res

##消除两个符号

def remove(formula):

    formula = formula.replace("+-","-")

    formula = formula.replace("-+", "-")

    formula = formula.replace("++", "+")

    formula = formula.replace("--", "-")

    formula = formula.replace("- -", "+")

    return formula

##处理特殊情况1 - 2 * -14969036.7968254   ['-', '-'] ['1 ', ' 2 * ', '14969036.7968254']   ' 2 * '

def special_done(a,b):

    for index,i in enumerate(b):

        i = i.strip()

        if i.endswith("*") or i.endswith("/"):

            b[index] = b[index] + a[index] + b[index + 1]

            del b[index + 1]

            del a[index]

    return a,b

#具体运算

def compute(formula):

    #print(formula)

    formula = formula.strip('()')

    a = re.findall(r'[+-]',formula)

    b = re.split(r'[+-]',formula)

    if len(b[0].strip()) == 0:  ##判断如果第一个是减号，值为空了无法运算，将其减号赋下一个值

        b[1] = a[0] + b[1]

        del a[0]

        del b[0]

    #print(a)

    #print(b)

    a,b = special_done(a,b)

    for index,i in enumerate(b):

        if re.search(r'[*/]',i):

            res = compute_mutiply_and_dividend(i)

            b[index] = res

    #print(b)

    ##开始运算+ -

    total_res = None

    for index,i in enumerate(b):

        if total_res:

            if a[index - 1] == "+":

                total_res += float(i)

            elif a[index - 1] == "-":

                total_res -= float(i)

        else:

            total_res = float(i)

    #print("\033[32;1m[%s]运算结果:\033[0m" % formula, total_res)

    return total_res

#主逻辑

def calc(formula):

    calc_status = True

    calc_res = None

    while calc_status:

        m = re.search(r'\([^()]*\)',formula)

        if m:

            sub_res = compute(m.group())

            formula = formula.replace(m.group(),str(sub_res))

            formula = remove(formula)

            #print(formula)

        else:

            #print('\033[41;1m----没拓号了...---\033[0m')

            print('\n\n\033[42;1m最终结果:\033[0m', compute(formula))

            calc_status = False

            print("计算结束")

calc(sys.argv[1])

print("eval的计算结果：",eval(sys.argv[1]))

3.程序执行输出