说明
该计算器主要是为了练习正则表达式以及python基础所写：代码比较low！
运行过程
请输入你的计算公式, 计算器会将计算结果输出到屏幕上(此处会打印步骤); 退出（exit/quit）
MyCalc> 1 - 2 * ( (60-30 +(-40/5) * (9-2*5/3 + 7 /3*99/4*2998 +10 * 568/14 )) - (-4*3)/ (16-3*2) ) 1-2*((60-30+(-40/5)*(9-2*5/3+7/3*99/4*2998+10*568/14))-(-4*3)/(16-3*2)) ----------- 步骤 [] ['-40/5'] (-40/5) 运算结果: -8.0 parenthesis_calc_result: 1-2*((60-30+-8.0*(9-2*5/3+7/3*99/4*2998+10*568/14))-(-4*3)/(16-3*2)) ----------- 步骤 ['-', '+', '+'] ['9', '2*5/3', '7/3*99/4*2998', '10*568/14'] (9-2*5/3+7/3*99/4*2998+10*568/14) 运算结果: 173545.88095238098 parenthesis_calc_result: 1-2*((60-30-8.0*173545.88095238098)-(-4*3)/(16-3*2)) ----------- 步骤 ['-', '-'] ['60', '30', '8.0*173545.88095238098'] (60-30-8.0*173545.88095238098) 运算结果: -1388337.0476190478 parenthesis_calc_result: 1-2*(-1388337.0476190478-(-4*3)/(16-3*2)) ----------- 步骤 [] ['-4*3'] (-4*3) 运算结果: -12.0 parenthesis_calc_result: 1-2*(-1388337.0476190478--12.0/(16-3*2)) ----------- 步骤 ['-'] ['16', '3*2'] (16-3*2) 运算结果: 10.0 parenthesis_calc_result: 1-2*(-1388337.0476190478+12.0/10.0) ----------- 步骤 ['+'] ['-1388337.0476190478', '12.0/10.0'] (-1388337.0476190478+12.0/10.0) 运算结果: -1388335.8476190479 parenthesis_calc_result: 1-2*-1388335.8476190479 ----------- 步骤 ['-'] ['1', '2*-1388335.8476190479'] 1-2*-1388335.8476190479 运算结果: 2776672.6952380957 最后的运算结果: 2776672.6952380957
具体代码实现
#/usr/bin/env python3
# _*_ coding: utf-8 _*_
__author__ = 'rianley cheng'
__blog__ ='https://www.cnblogs.com/rianley'
'''
left is too short , I use python !
数据规范化， 正则拆分，结合运算 打印运算表达式及运算步骤
'''
import re,time
def math_legal(num): #判断输入公式是否合法，如包含字符或者特殊字符，做特殊处理
try:
num = float(num)
return True
except (ValueError,TypeError) as diag:
pass
def calc_formula(formula): #替换多余的加减操作
formula = formula.replace("++", "+")
formula = formula.replace("+-", "-")
formula = formula.replace("-+", "-")
formula = formula.replace("--", "+")
return formula
def match_calc_formula(parenthesises_formula): #匹配加减操作符和加减表达式列表
# 取出圆括号表达式中所有的"+-"号，保存为列表形式，如['-', '+', '+']
# 用"+-"号作为分隔符，将圆括号中的乘除表达式取出，保存为列表形式，如['9', '2*5/3', '7/3*99/4*2998', '10*568/14']
parenthesises_formula = re.sub("[()]", "", parenthesises_formula)
plusminus_operator_list = re.findall("[+-]", parenthesises_formula)
plusminus_expression_list = re.split("[+-]", parenthesises_formula)
if plusminus_expression_list[0] == "":
#圆括号表达式列表中，如果第一个元素为空，则表明第一个元素为一个负数，则"-"号开头，将第一个"-"号合并到列表第一个元素
plusminus_expression_list[1] = plusminus_operator_list[0] + plusminus_expression_list[1]
del plusminus_expression_list[0]
del plusminus_operator_list[0]
for i, e in enumerate(plusminus_expression_list):
#处理成正确的结果：['1 * -2', '3 * -5', '6/-3']
e = e.strip()
if e.endswith("*") or e.endswith("/"):
try:
plusminus_expression_list[i] = plusminus_expression_list[i] + plusminus_operator_list[i] + plusminus_expression_list[i + 1]
del plusminus_expression_list[i + 1]
del plusminus_operator_list[i]
except IndexError as diag:
pass
return plusminus_operator_list,plusminus_expression_list
def matching_multiply_divide_operator(plusminus_equations): #匹配乘除操作符和乘除表达式列表
operator_list = re.findall("[*/]", plusminus_equations)
value_list = re.split("[*/]", plusminus_equations)
return operator_list,value_list
def plus_minus_calc(plusminus_operator_list,plusminus_expression_list): #加减运算
'''对运算公式进行加减运算，返回加减结果'''
plusminus_result = None
for i, e in enumerate(plusminus_expression_list):
match = math_legal(e)
if match == True:
if plusminus_result:
if plusminus_operator_list[i - 1] == "+":
plusminus_result += float(e)
elif plusminus_operator_list[i - 1] == "-":
plusminus_result -= float(e)
else:
plusminus_result = float(e)
else:
print("33[33;0m输入的公式中包含非数字字符!33[0m")
print("33[33;0m尝试运算: %s33[0m" % e)
e = re.sub("D", "", e)
if e == "": e = 0
if plusminus_result:
if plusminus_operator_list[i - 1] == "+":
plusminus_result += float(e)
elif plusminus_operator_list[i - 1] == "-":
plusminus_result -= float(e)
else:
try:
plusminus_result = float(e)
except ValueError as diag:
print("33[33;1m无效输入！33[0m")
return plusminus_result
def multiply_divide_calc(multiply_divide_operator_list,multiply_divide_value_list): #乘除运算
'''对运算公式进行乘除运算，返回乘除结果'''
multiply_divide_result = None
for i, num in enumerate(multiply_divide_value_list):
match = math_legal(num)
if match == True:
if multiply_divide_result:
if multiply_divide_operator_list[i - 1] == "*":
multiply_divide_result *= float(num)
elif multiply_divide_operator_list[i - 1] == "/":
try:
multiply_divide_result /= float(num)
except ZeroDivisionError as diag:
multiply_divide_result = 0
print("33[33;0m输入的公式中存在除数为0，重新输入！33[0m")
else:
multiply_divide_result = float(num)
else:
print("33[33;0m输入的公式中存在无法识别的内容!33[0m")
print("33[33;0m尝试为您运算: %s33[0m" % num)
num = re.sub("D", "", num)
if num == "": num = 1
if multiply_divide_result:
if multiply_divide_operator_list[i - 1] == "*":
multiply_divide_result *= float(num)
elif multiply_divide_operator_list[i - 1] == "/":
multiply_divide_result /= float(num)
else:
try:
multiply_divide_result = float(num)
except ValueError as diag:
print("33[33;1m无效输入！33[0m")
return multiply_divide_result
def calculating_priority_formulas(priority_formula): #计算圆括号表达式
""""""
plusminus_operator_list, plusminus_expression_list = match_calc_formula(priority_formula)
print("-----------")
print("33[31;1m步骤33[0m")
print(plusminus_operator_list, plusminus_expression_list)
for index, equations in enumerate(plusminus_expression_list):
if "*" in equations or "/" in equations:
""""""
multiply_divide_operator_list, multiply_divide_value_list = matching_multiply_divide_operator(equations)
multiply_divide_result = multiply_divide_calc(multiply_divide_operator_list, multiply_divide_value_list) #取出乘除表达式进行乘除运算
plusminus_expression_list[index] = multiply_divide_result
plus_minus_result = plus_minus_calc(plusminus_operator_list, plusminus_expression_list) #将乘除的结果进行加减运算
print("%s 运算结果: %s" % (priority_formula, plus_minus_result))
return plus_minus_result
def start_operation(formula):
""" 运算主程序入口，对输入的数学公式进行处理，匹配最底层圆括号表达式，并交给乘除函数计算返回结果，替换圆括号表达式"""
formula = formula.replace(" ", "") #去掉表达式多余的空格
formula = calc_formula(formula) #去掉表达式里重复的"+-"号
print(formula)
parenthesises_flag = True
while parenthesises_flag:
formula = calc_formula(formula)
parenthesis_formula = re.search(r"(([^()]+))", formula)
if parenthesis_formula:
parenthesis_formula = parenthesis_formula.group()
parenthesis_calc_result = calculating_priority_formulas(parenthesis_formula)
formula = formula.replace(parenthesis_formula, str(parenthesis_calc_result))
print("parenthesis_calc_result: %s" % formula)
else:
calc_result = calculating_priority_formulas(formula)
parenthesises_flag = False
print("最后的运算结果: 33[31;1m%s33[0m" % calc_result)
def myCalcMain():
prompt = '''
请输入你的计算公式, 计算器会将计算结果输出到屏幕上(此处会打印步骤); 退出（exit/quit）
示例公式: 1 - 2 * ( (60-30 +(-40/5) * (9-2*5/3 + 7 /3*99/4*2998 +10 * 568/14 )) - (-4*3)/ (16-3*2) )
'''
print(prompt)
while True:
formula = input("MyCalc> ").strip()
if formula == "exit" or formula == "quit":
print('欢迎下次使用，欢迎关注作者博客！（https://cnblogs.com/rianley）更多资讯敬请期待')
time.sleep(3)
exit("Bye.Bye...")
elif formula == "":
continue
else:
start_operation(formula)
if __name__ == '__main__':
myCalcMain()
结言
努力成为想要成为的人，就算最后失败了！也没关系，因为遗憾比失败可怕的多！