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：1071179133@qq.com
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