如下所示，要求通过不同的函数来实现四则运算，该怎么做？

Question

编写程序，从键盘输入两个数字 并选择一种算术四则运算，然后输出运算结果。要求通过不同的函数来实现四则运算，并定义一个接受两个操作数和一个函数名称的函数，函数名称用于指定做哪种运算

Answer 1

import re

class OPERATION(object):
def __init__(self, a, b,ys):
self.a = a
self.b = b
self.ys=ys

def addition(self):
result = self.a + self.b
print(' = %s' % result)
return result

def subtraction(self):
result = self.a - self.b

print(' = %s' % result)
return result

def  multiplication (self):
result = self.a * self.b
print(' = %s' % result)
return result

def division(self):
if self.b==0:
return print("输入有误")
else:
result = self.a / self.b
print(' = %s' % result)
return result

def operation(self):
if self.ys is '+':
OPERATION.addition(self)
elif self.ys is '-':
OPERATION.subtraction(self)
elif self.ys is '*':
OPERATION. multiplication (self)
elif self.ys is '/':
OPERATION.division(self)
else:
print("暂时没有实现这种运算")
def main():
print("请输要计算的算式，如 a+b 按回车键查看结果,输入exit退出")
while True:
str = input(">>")
if str =='exit':
break;
else:
ret = re.match(r'^(\d+)([\+\-\*/]+)(\d+)', str)
if ret:
numa = int(ret.group(1))
operationalCharacter = ret.group(2)
numb = int(ret.group(3))
print(numa, operationalCharacter, numb,end='')
yunsuan = OPERATION(numa, numb,operationalCharacter)
yunsuan.operation()
else:
print("请检查输入是否正确")

if __name__=='__main__':
main()

运行结果

Answer 2