python_41_with语句

#为了避免打开文件后忘记关闭，可以通过管理上下文，即：with open('log','r') as f:
# 如此方式，当with代码块执行完毕时，内部会自动关闭并释放文件资源。
with open('yesterday','r',encoding='utf-8') as f:
    for line in f:#只是个例子
        print(line)
#注：python规范，一行代码不要超过80个字符。
#在Python 2.7 后，with又支持同时对多个文件的上下文进行管理，即：with open('log1') as obj1, open('log2') as obj2:
with open('yesterday','r',encoding='utf-8') as f,
    open('yyy','r',encoding='utf-8') as f1:
    for line in f:#只是个例子
        print(line)
with open('mmm','w',encoding='utf-8') as f:
   f.write('aaaa')