034丰富的else语句及简洁的with语句

人若有情死得早

1.丰富的else语句
1)要么怎样，要么不怎样
If...else...
2)干完了能怎样，干不完就别想怎样

1. def showMaxFactor(num):
   
2.     count = num // 2
   
3.     while count > 1:
   
4.         if num % count == 0:
   
5.             print ('%d最大的约数是%d' % (num, count))
   
6.             break
   
7.         count -= 1
   
8.     else:
   
9.         print('%d是素数!' % num)
   
10. 
    
11. num = int(input('请输入一个数:'))
    
12. showMaxFactor(num)
    
13. 
    
14. 请输入一个数:25
    
15. 25最大的约数是5
    
16. 
    
17. 请输入一个数:11
    
18. 11是素数!

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3)没有问题，那就干吧

1. try:
   
2.     int('abc')
   
3. except ValueError as reason:
   
4.     print('出错啦:' + str(reason))
   
5. else:
   
6. print('没有任何异常!')
   
7. 出错啦:invalid literal for int() with base 10: 'abc'

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1. try:
   
2.     int('abc')
   
3. except ValueError as reason:
   
4.     print('出错啦:' + str(reason))
   
5. else:
   
6. print('没有任何异常!')
   
7. 没有任何异常!

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1. try:
   
2.     print(int('123'))
   
3. except ValueError as reason:
   
4.     print('出错啦:' + str(reason))
   
5. else:
   
6.     print('没有任何异常!')
   
7. 123
   
8. 没有任何异常!

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1. try:
   
2.     print(int('abc'))
   
3. except ValueError as reason:
   
4.     print('出错啦:' + str(reason))
   
5. else:
   
6.     print('没有任何异常!')
   
7. 出错啦:invalid literal for int() with base 10: 'abc'

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2.简洁的with语句

1. try:
   
2.     f = open('data.txt', 'w')
   
3.     for each_line in f:
   
4.         print(each_line)
   
5. except OSError as reason:
   
6.     print('出错啦:' + str(reason))
   
7. finally:
   
8. f.close()
   
9. 出错啦:not readable

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1. try:
   
2.     with open('data.txt', 'w') as f:
   
3.         for each_line in f:
   
4.             print(each_line)
   
5. except OSError as reason:
   
6. print('出错啦:' + str(reason))
   
7. 出错啦:not readable

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