标签：
Python文件
文件操作流程
1、打开文件，得到文件句柄并赋值给一个变量
2、通过句柄对文件进行操作
3、关闭文件
打开文件的模式
r ，只读模式【默认】
w，只写模式【不可读；不存在则创建；存在则清空内容；】
x， 只写模式【不可读；不存在则创建，存在则报错】
a， 追加模式【可读； 不存在则创建；存在则只追加内容；】
"+" 表示可以同时读写某个文件
r+， 读写【可读，可写】
w+，写读【可读，可写】
x+ ，写读【可读，可写】
a+， 写读【可读，可写】
"b"表示以字节的方式操作
rb 或 r+b
wb 或 w+b
xb 或 w+b
ab 或 a+b
注：以b方式打开时，读取到的内容是字节类型，写入时也需要提供字节类型
通过with open("test.txt") as f 可以不用主动去关闭文件，程序会自动对文件进行关闭
重点是读写这块需要注意下
现有文件内容如下：
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Somehow, it seems the love I knew was always the most destructive kindYesterday when I was youngThe taste of life was sweetAs rain upon my tongueI teased at life as if it were a foolish gameThe way the evening breezeMay tease the candle flameThe thousand dreams I dreamedThe splendid things I planned |
通过read的方式去读取文件内容:
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#read将文件内容一次性全部读取出来>>> with open("test.txt") as f:... print (f.read())... Somehow, it seems the love I knew was always the most destructive kindYesterday when I was youngThe taste of life was sweetAs rain upon my tongueI teased at life as if it were a foolish gameThe way the evening breezeMay tease the candle flameThe thousand dreams I dreamedThe splendid things I planned |
通过readline的方式去读取文件内容:
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#readline是将文件内容一行行的读取，每执行一次读取一行>>> with open("test.txt") as f:... flag = True... while flag:... line = f.readline()... if line:... print (line)... else:... flag = False... Somehow, it seems the love I knew was always the most destructive kind Yesterday when I was young The taste of life was sweet As rain upon my tongue I teased at life as if it were a foolish game The way the evening breeze May tease the candle flame The thousand dreams I dreamed The splendid things I planned |
通过readlines的方式去读取文件内容:
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#readlines是将整个文件内容以列表的形式读取出来>>> with open("test.txt") as f:... print (f.readlines())... [‘Somehow, it seems the love I knew was always the most destructive kind\n‘, ‘Yesterday when I was young\n‘, ‘The taste of life was sweet\n‘, ‘As rain upon my tongue\n‘, ‘I teased at life as if it were a foolish game\n‘, ‘The way the evening breeze\n‘, ‘May tease the candle flame\n‘, ‘The thousand dreams I dreamed\n‘, ‘The splendid things I planned\n‘]#遍历文件内容>>> with open("test.txt") as f:... for line in f.readlines():... print (line)... Somehow, it seems the love I knew was always the most destructive kindYesterday when I was youngThe taste of life was sweetAs rain upon my tongueI teased at life as if it were a foolish gameThe way the evening breezeMay tease the candle flameThe thousand dreams I dreamedThe splendid things I planned |
直接遍历文件内容：
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>>> with open("test.txt") as f:... for line in f:... print (line)... Somehow, it seems the love I knew was always the most destructive kindYesterday when I was youngThe taste of life was sweetAs rain upon my tongueI teased at life as if it were a foolish gameThe way the evening breezeMay tease the candle flameThe thousand dreams I dreamedThe splendid things I planned |
下面是以各种方式打开文件之后写入"hello world"之后的文件内容
以 r+ 的方式打开文件进行写操作后的内容(可以看到文件的前面的字符被替换了):
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hello world seems the love I knew was always the most destructive kindYesterday when I was youngThe taste of life was sweetAs rain upon my tongueI teased at life as if it were a foolish gameThe way the evening breezeMay tease the candle flameThe thousand dreams I dreamedThe splendid things I planned |
以w+的方式打开文件进行写操作后的内容(可以看到里面的内容被清空后再写入的):
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hello world |
以a+的方式打开文件进行读写操作后的内容(可以看到hello world追加到了文件最后面):
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Somehow, it seems the love I knew was always the most destructive kindYesterday when I was youngThe taste of life was sweetAs rain upon my tongueI teased at life as if it were a foolish gameThe way the evening breezeMay tease the candle flameThe thousand dreams I dreamedThe splendid things I plannedhello world |
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原文地址：http://www.cnblogs.com/Kingway-Python/p/5840561.html
