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

def showMaxFactor(num):
    count = num // 2
    while count > 1:
        if num % count == 0:
            print ('%d最大的约数是%d' % (num, count))
            break
        count -= 1
    else:
        print('%d是素数!' % num)

num = int(input('请输入一个数:'))
showMaxFactor(num)

请输入一个数:25
25最大的约数是5

请输入一个数:11
11是素数!

3)没有问题，那就干吧

try:
    int('abc')
except ValueError as reason:
    print('出错啦:' + str(reason))
else:
print('没有任何异常!')
出错啦:invalid literal for int() with base 10: 'abc'

try:
    int('abc')
except ValueError as reason:
    print('出错啦:' + str(reason))
else:
print('没有任何异常!')
没有任何异常!

try:
    print(int('123'))
except ValueError as reason:
    print('出错啦:' + str(reason))
else:
    print('没有任何异常!')
123
没有任何异常!

try:
    print(int('abc'))
except ValueError as reason:
    print('出错啦:' + str(reason))
else:
    print('没有任何异常!')
出错啦:invalid literal for int() with base 10: 'abc'

2.简洁的with语句

try:
    f = open('data.txt', 'w')
    for each_line in f:
        print(each_line)
except OSError as reason:
    print('出错啦:' + str(reason))
finally:
f.close()
出错啦:not readable

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))
出错啦:not readable