用python画枫叶-Python中的用for,while循环遍历文件实例

使用for循环遍历文件

打开文件

open

r:以读模式打开

w:以写模式打开

a:以追加模式打开

r+:以读写模式打开

w+:以读写模式打开(参见w)

a+:以读写模式打开(参见a)

rb:以二进制读模式打开

wb:以二进制写模式打开(参见w)

ab:以二进制追加模式打开(参见a)

rb+:以二进制读写模式打开(参见r+)

wb+:以二进制读写模式打开(参见w+)

ab+:以二进制读写模式打开(参见a+)

查看帮助:

open(...)

open(name[, mode[, buffering]]) -> file object

Open a file using the file() type, returns a file object. This is the

preferred way to open a file. See file.__doc__ for further information.

(END)...skipping...

[root[@localhost](https://my.oschina.net/u/570656) ~]# cat /tmp/1.txt

1111

[root[@localhost](https://my.oschina.net/u/570656) ~]#

只读方式打开:

In [26]: open('/tmp/1.txt')

Out[26]:

In [27]: fd = open('/tmp/1.txt')

In [28]: fd

Out[28]:

In [29]: type(fd)

Out[29]: file

以写方式打开:

In [34]: fd = open('/tmp/1.txt','w')

In [35]: fd.write('2222 ')

In [36]: fd.close()

[root[@localhost](https://my.oschina.net/u/570656) ~]# cat /tmp/1.txt

2222

[root[@localhost](https://my.oschina.net/u/570656) ~]#

以追加方式打开:

In [34]: fd = open('/tmp/1.txt','a')

In [35]: fd.write('3333 ')

In [36]: fd.close()

[root[@localhost](https://my.oschina.net/u/570656) ~]# cat /tmp/1.txt

2222

3333

[root@localhost ~]#

read():

In [41]: fd.read()

Out[41]: '2222 3333 '

In [42]: fd.read()

Out[42]: ''

In [49]: fd.readline()

Out[49]: '2222 '

In [50]: fd.readline()

Out[50]: '3333 '

In [51]: fd.readline()

Out[51]: ''

In [52]:

read() 和readline()返回的是字符串:

readlines()返回的是列表:

in [52]: fd = open('/tmp/1.txt')

In [53]: fd.readlines()

Out[53]: ['2222 ', '3333 ']

脚本:

#!/usr/bin/python

fd = open('/tmp/1.txt')

for line in fd:

print line,

fd.close()

[root@localhost 20171228]# python read_file.py

2222

3333

[root@localhost 20171228]#

使用while循环遍历文件

脚本:

#!/usr/bin/python

fd = open('/tmp/1.txt')

while True:

line = fd.readline()

if not line:

break

print line,

fd.close()

[root@localhost 20171228]# python read_fi_while.py

2222

3333

[root@localhost 20171228]#

with open打开文件 :

#!/usr/bin/python

with open('/tmp/1.txt') as fd:

while True:

line = fd.readline()

if not line:

break

print line,

你可能感兴趣的:(用python画枫叶-Python中的用for,while循环遍历文件实例)