else与with语句
else
if…else…
a
= input("请输入：")
if int(a
) % 2 == 0:
print(a
+ '是一个偶数!')
else:
print(a
+ '是一个奇数！')
请输入：
5
5是一个奇数！
try…except…else…
a
= input("请输入：")
try:
int(a
)
except ValueError
as reason
:
print(str(reason
))
else:
print('there is no error!')
请输入：
1
there is no error
!
#############################################
a
= input("请输入：")
try:
int(a
)
except ValueError
as reason
:
print(str(reason
))
else:
print('there is no error!')
请输入：jh
invalid literal
for int() with base
10: 'jh'
with
你可以反复调用write()来写入文件，但是务必要调用f.close()来关闭文件。
try:
f
= open('D:/python/foo1.txt', 'r')
print(f
.read())
finally:
if f
:
f
.close()
xdgdf3noob
.com
!
Very good site
!
www
.runoob
.com
!
Very good site
!
xdgdf
但是with语句更加简洁，再也不用担心文件打开之后忘记close的问题了：
with open('D:/python/foo1.txt', 'r') as f
:
print(f
.read())
xdgdf3noob
.com
!
Very good site
!
www
.runoob
.com
!
Very good site
!
xdgdf
