跟老齐学Python之不要红头文件(1)

>>> dir(file)
['__class__', '__delattr__', '__doc__', '__enter__', '__exit__', '__format__', '__getattribute__', '__hash__', '__init__', '__iter__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', 'close', 'closed', 'encoding', 'errors', 'fileno', 'flush', 'isatty', 'mode', 'name', 'newlines', 'next', 'read', 'readinto', 'readline', 'readlines', 'seek', 'softspace', 'tell', 'truncate', 'write', 'writelines', 'xreadlines']

>>> f = open("130.txt")   #打开已经存在的文件
>>> for line in f:
...   print line
... 
learn python

http://qiwsir.github.io

qiwsir@gmail.com

>>> f = open('130.txt')
>>> for line in f:
...   print line,   #后面加一个逗号，就去掉了原来默认增加的\n了，看看，少了空行。
... 
learn python
http://qiwsir.github.io
qiwsir@gmail.com

>>> f = open('130.txt')
>>> for line in f:
...   print line,
... 
learn python
http://qiwsir.github.io
qiwsir@gmail.com

>>> for line2 in f:   #在前面通过for循环读取了文件内容之后，再次读取，
...   print line2   #然后打印，结果就什么也显示，这是什么问题？
... 
>>>

>>> f = open("130.txt")
Traceback (most recent call last):
 File "", line 1, in 
IOError: [Errno 2] No such file or directory: '130.txt'

>>> f = open("./codes/130.txt")   #必须得写上路径了（注意，windows的路径是\隔开，需要转义。对转义符，看官看以前讲座）
>>> for line in f:
...   print line
... 
learn python

http://qiwsir.github.io

qiwsir@gmail.com

>>> 

>>> nf = open("131.txt","w")
>>> nf.write("This is a file")

>>> f = open("130.txt")
>>> f

>>> f = open("130.txt","r")
>>> f

>>> fp = open("131.txt")
>>> for line in fp:     #原来这个文件里面的内容
...   print line
... 
This is a file
>>> fp = open("131.txt","w")  #这时候再看看这个文件，里面还有什么呢？是不是空了呢？
>>> fp.write("My name is qiwsir.\nMy website is qiwsir.github.io") #再查看内容
>>> fp.close()

$ cat 131.txt #cat是linux下显示文件内容的命令，这里就是要显示131.txt内容
My name is qiwsir.
My website is qiwsir.github.io

>>> fp = open("131.txt","a")
>>> fp.write("\nAha,I like program\n")  #向文件中追加
>>> fp.close()              #这是关闭文件，一定要养成一个习惯，写完内容之后就关闭

$ cat 131.txt
My name is qiwsir.
My website is qiwsir.github.io
Aha,I like program