Python使用try...except...来处理异常，当Python遇到一个try语句，他会尝试执行try语句体内的语句，如果执行这些语句没有错误，控制转移到try...except...后面的语句，如果语句体内发生错误，python会寻找一个符合该错误的异常语句，然后执行处理代码。
try:<body>
except <ErrorType1>:<handler1>
except <ErrorType2>:<handler2>
else:<process_else>
finally:<process_finally>try体内如果无异常产生，则执行else语句；
无论try体内无论是否有异常，finally语句都会执行，finally一般是无论是否异常发生都要执行清理的工作，比如打开后文件需要关闭文件的操作，连接网络后需要断开网络的操作。
我们的测试代码如下：
def main():while True:try:number1, number2 = eval(input('Enter two number,separated by a comma:'))result = number1 / number2except ZeroDivisionError:print('Division by zero!')except SyntaxError:print('A comma may be missing in the input')except:print('Something wrong in the input')else:print('No exception,the result is:', result)breakfinally:print('executing the final clause')
main()
测试数据如下：
Enter two number,separated by a comma:3,4
No exception,the result is: 0.75
executing the final clauseEnter two number,separated by a comma:2,0
Division by zero!
executing the final clause
Enter two number,separated by a comma:
)
