作业需求：
模拟计算器开发：
实现加减乘除及拓号优先级解析
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
思路解析:
1. 先实现基本+-*/
2. 使用re正则模块优先解析最内测的拓号进行运算
程序核心代码：
#!/usr/bin/env python
# -*- coding:utf-8 -*-
# Author: Colin Yao
"""模拟计算器开发作业"""
import re
def operator_update(formula):
formula = formula.replace(" ", "")
formula = formula.replace("+-", "-")
formula = formula.replace("--", "+")
return formula
def calc_muldiv(formula_list):
for index, element in enumerate(formula_list):
if "*" in element or "/" in element:
operators = re.findall("[*/]", element)
calc_list = re.split("[*/]", element)
num = None
for i, e in enumerate(calc_list):
if num:
if operators[i - 1] == "*":
num *= float(e)
elif operators[i - 1] == "/":
num /= float(e)
else:
num = float(e)
formula_list[index] = num
return formula_list
def calc_plumin(operators, num_list):
num = None
for i, e in enumerate(num_list):
if num:
if operators[i - 1] == "+":
num += float(e)
elif operators[i - 1] == "-":
num -= float(e)
else:
num = float(e)
return num
def merge(plus_minus_operator, multiply_divide_list):
for index, element in enumerate(multiply_divide_list):
if element.endswith("*") or element.endswith("/"):
multiply_divide_list[index] = element + plus_minus_operator[index] + multiply_divide_list[index + 1]
del multiply_divide_list[index + 1]
del plus_minus_operator[index]
return merge(plus_minus_operator, multiply_divide_list)
return plus_minus_operator, multiply_divide_list
def bracket_calc(formula):
formula = re.sub("[()]", "", formula) # 去除两边的（）
formula = operator_update(formula)
plus_minus_operator = re.findall("[+-]", formula)
multiply_divide_list = re.split("[+-]", formula)
if multiply_divide_list[0] == "":
multiply_divide_list[1] = "-" + multiply_divide_list[1]
del plus_minus_operator[0]
del multiply_divide_list[0]
res = merge(plus_minus_operator, multiply_divide_list)
plus_minus_operator = res[0]
multiply_divide_list = res[1]
plus_minus_list = calc_muldiv(multiply_divide_list)
res = calc_plumin(plus_minus_operator, plus_minus_list)
return res
def calculate(formula):
while True:
formula_depth = re.search("\([^()]+\)", formula)
if formula_depth:
formula_depth = formula_depth.group()
res = bracket_calc(formula_depth)
formula = formula.replace(formula_depth, str(res))
print(formula)
else:
res = bracket_calc(formula)
print(res)
exit()
if __name__ == '__main__':
msg = '''
进行解析()的运算
例如:1 - 2 * ( (60-30 +(-40/5) * (9-2*5/3 + 7 /3*99/4*2998 +10 * 568/14 )) - (-4*3)/ (16-3*2) )
'''
print(msg)
formula = input("请输入要进行的运算>>>:")
# formula = "1 - 2 * ( (60-30 +(-40/5) * (9-2*5/3 + 7 /3*99/4*2998 +10 * 568/14 )) - (-4*3)/ (16-3*2) )"
calculate(formula)
程序测试样图:
