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在Python中,else语句不仅能跟if语句搭配,构成“要么怎样,要么不怎么样”的语境;Ta还能跟循环语句(for语句或者while语句),构成“干完了能怎样,不干完就别想怎样”的语境;其实else语句还能够跟我们刚刚讲的异常处理进行搭配,构成“没有问题,那就干吧”的语境。
eg:
def showMaxFactor(num): count = num // 2#//为整除,判断是素数,只需依次判断当前数num除以1到(num // 2)都不能整除即可 while count > 1: if num % count == 0:#判断是否整除 print('%d最大的约数是%d' % (num, count)) break#跳出循环后else并不执行 count -= 1 else:#当while循环不成立时,或者理解为while循环完全被执行完了,没有给中途跳出(即break) print('%d是素数!' % num)num = int(input('请输入一个数:'))showMaxFactor(num)
try: print(int('123'))except ValueError as reason: print('出错了:' + str(reason))else: print('没有任何异常!')
try: f = open('test.txt','w') for each_line in f: print(each_line)except (OSError,TypeError) as reason: print('出错了\n原因是:' + str(reason))finally: f.close()
try: with open('test.txt','w') as f: for each_line in f: print(each_line)except (OSError,TypeError) as reason: print('出错了\n原因是:' + str(reason))
测试:
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