python__异常

try:
f = open("我是")
print f
f.close()
except OSError as reason:
print('文件出错了:' + str(reason))

with:可以自动关闭文件流，而不用手动关闭
try:
with open('dat.txt','w') as f:
for each_line in f:
print(each_line);
except OSError as reason:
print('出错了：'+reason)