python文件读写

1. 最基本的读文件方法：

File: readline-example-1.py

file = open("sample.txt")while 1:    line = file.readline()    if not line:        break    pass # do something

一行一行得从文件读数据，显然比较慢；不过很省内存。

2. 用fileinput模块

# File: readline-example-2.pyimport fileinputfor line in fileinput.input("sample.txt"):    pass

3. 带缓存的文件读取

# File: readline-example-3.pyfile = open("sample.txt")while 1:    lines = file.readlines(100000)    if not lines:        break    for line in lines:        pass # do something

在Python 2.2以后，我们可以直接对一个file对象使用for循环读每行数据：

# File: readline-example-5.pyfile = open("sample.txt")for line in file:    pass # do something

而在Python 2.1里，你只能用xreadlines迭代器来实现：

# File: readline-example-4.pyfile = open("sample.txt")for line in file.xreadlines():    pass # do something