else与with

1 else与while while：语句 else：否则就，与ifelse类似，可参考

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)

2 else与try except拦截错误类型，else截取剩下的结果，可以参考我上一天博客了解try

try: int('abc') except ValueError as reason: print('出错') else: print('没错'） try: int('abc') except ValueError as reason: print('出错') else: print('没错'

3.with语句

try: with open('data.txt','w') as f: for each_line in f: print(each_line) except OSError as reason: print('出错啦：' + str(reason))

with open(…) as f 　　下面的语句不用写close方法关闭文件，with语句会自动考虑帮助关闭文件