Python-Basis-12th
周三，晴，记录生活分享点滴
参考博客：https://www.cnblogs.com/alex3714/articles/5169958.html
Python版本：3.5
计算器
需求
1. 实现加减乘除及括号优先级解析
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，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
示例
构建
import re import functools def minus_operator_handler(formula): '''处理一些特殊的减号运算''' minus_operators = re.split("-", formula) calc_list = re.findall("[0-9]", formula) if minus_operators[0] == '': # 第一值肯定是负号 calc_list[0] = '-%s' % calc_list[0] res = functools.reduce(lambda x, y: float(x) - float(y), calc_list) print("\033[33;1m减号[%s]处理结果:\033[0m" % formula, res) return res def remove_duplicates(formula): formula = formula.replace("++", "+") formula = formula.replace("+-", "-") formula = formula.replace("-+", "-") formula = formula.replace("--", "+") formula = formula.replace("- -", "+") return formula def compute_mutiply_and_dividend(formula): '''算乘除,传进来的是字符串噢''' operators = re.findall("[*/]", formula) calc_list = re.split("[*/]", formula) res = None for index, i in enumerate(calc_list): if res: if operators[index - 1] == "*": res *= float(i) elif operators[index - 1] == "/": res /= float(i) else: res = float(i) print("\033[31;1m[%s]运算结果=\033[0m" % formula, res) return res def handle_minus_in_list(operator_list, calc_list): '''有的时候把算术符和值分开后,会出现这种情况 ['-', '-', '-'] [' ', '14969037.996825399 ', ' ', '12.0/ 10.0 '] 这需要把第2个列表中的空格都变成负号并与其后面的值拼起来,恶心死了 ''' for index, i in enumerate(calc_list): if i == '': # 它其实是代表负号,改成负号 calc_list[index + 1] = i + calc_list[index + 1].strip() def handle_special_occactions(plus_and_minus_operators, multiply_and_dividend): '''有时会出现这种情况 , ['-', '-'] ['1 ', ' 2 * ', '14969036.7968254'],2*...后面这段实际是 2*-14969036.7968254,需要特别处理下,太恶心了''' for index, i in enumerate(multiply_and_dividend): i = i.strip() if i.endswith("*") or i.endswith("/"): multiply_and_dividend[index] = multiply_and_dividend[index] + plus_and_minus_operators[index] + \ multiply_and_dividend[index + 1] del multiply_and_dividend[index + 1] del plus_and_minus_operators[index] return plus_and_minus_operators, multiply_and_dividend def compute(formula): '''这里计算是的不带括号的公式''' formula = formula.strip("()") # 去除外面包的括号 formula = remove_duplicates(formula) # 去除外重复的+-号 plus_and_minus_operators = re.findall("[+-]", formula) multiply_and_dividend = re.split("[+-]", formula) # 取出乘除公式 if len(multiply_and_dividend[0].strip()) == 0: # 代表这肯定是个减号 multiply_and_dividend[1] = plus_and_minus_operators[0] + multiply_and_dividend[1] del multiply_and_dividend[0] del plus_and_minus_operators[0] plus_and_minus_operators, multiply_and_dividend = handle_special_occactions(plus_and_minus_operators, multiply_and_dividend) for index, i in enumerate(multiply_and_dividend): if re.search("[*/]", i): sub_res = compute_mutiply_and_dividend(i) multiply_and_dividend[index] = sub_res # 开始运算+,- print(multiply_and_dividend, plus_and_minus_operators) total_res = None for index, item in enumerate(multiply_and_dividend): if total_res: # 代表不是第一次循环 if plus_and_minus_operators[index - 1] == '+': total_res += float(item) elif plus_and_minus_operators[index - 1] == '-': total_res -= float(item) else: total_res = float(item) print("\033[32;1m[%s]运算结果:\033[0m" % formula, total_res) return total_res def calc(formula): '''计算程序主入口, 主要逻辑是先计算括号里的值,算出来后再算乘除,再算加减''' parenthesise_flag = True calc_res = None # 初始化运算结果为None,还没开始运算呢,当然为None啦 while parenthesise_flag: m = re.search("\([^()]*\)", formula) # 找到最里层的括号 if m: # print("先算括号里的值:",m.group()) sub_res = compute(m.group()) formula = formula.replace(m.group(), str(sub_res)) else: print('\033[41;1m----没括号了...---\033[0m') print('\n\n\033[42;1m最终结果:\033[0m', compute(formula)) parenthesise_flag = False # 代表公式里的括号已经都被剥除啦 if __name__ == '__main__': # res = calc("1 - 2 * ( (60-30 +(-40/5) * (9-2*5/3 + 7 /3*99/4*2998 +10 * 568/14 )) - (-4*3)/ (16-3*2) )") res = calc( "1 - 2 * ( (60-30 +(-9-2-5-2*3-5/3-40*4/2-3/5+6*3) * (-9-2-5-2*5/3 + 7 /3*99/4*2998 +10 * 568/14 )) - (-4*3)/ (16-3*2) )")
输出
# [2*3]运算结果= 6.0 # [5/3]运算结果= 1.6666666666666667 # [40*4/2]运算结果= 80.0 # [3/5]运算结果= 0.6 # [6*3]运算结果= 18.0 # ['-9', '2', '5', 6.0, 1.6666666666666667, 80.0, 0.6, 18.0] ['-', '-', '-', '-', '-', '-', '+'] # [-9-2-5-2*3-5/3-40*4/2-3/5+6*3]运算结果: -86.26666666666667 # [2*5/3 ]运算结果= 3.3333333333333335 # [ 7 /3*99/4*2998 ]运算结果= 173134.50000000003 # [10 * 568/14 ]运算结果= 405.7142857142857 # ['-9', '2', '5', 3.3333333333333335, 173134.50000000003, 405.7142857142857] ['-', '-', '-', '+', '+'] # [-9-2-5-2*5/3 + 7 /3*99/4*2998 +10 * 568/14 ]运算结果: 173520.88095238098 # [86.26666666666667 * 173520.88095238098]运算结果= 14969067.996825399 # ['60', '30 ', 14969067.996825399] ['-', '-'] # [60-30 -86.26666666666667 * 173520.88095238098]运算结果: -14969037.996825399 # [-4*3]运算结果= -12.0 # [-12.0] [] # [-4*3]运算结果: -12.0 # [3*2]运算结果= 6.0 # ['16', 6.0] ['-'] # [16-3*2]运算结果: 10.0 # [12.0/ 10.0 ]运算结果= 1.2 # ['-14969037.996825399 ', 1.2] ['+'] # [ -14969037.996825399 +12.0/ 10.0 ]运算结果: -14969036.7968254 # ----没括号了...--- # [ 2 * -14969036.7968254]运算结果= -29938073.5936508 # ['1 ', -29938073.5936508] ['-'] # [1 - 2 * -14969036.7968254]运算结果: 29938074.5936508 # 最终结果: 29938074.5936508
