python读写二进制文件的方法

本文实例讲述了python读写二进制文件的方法。分享给大家供大家参考。具体如下：

初学python，现在要读一个二进制文件，查找doc只发现 file提供了一个read和write函数，而且读写的都是字符串，如果只是读写char等一个字节的还行，要想读写如int,double等多字节数 据就不方便了。在网上查到一篇贴子，使用struct模块里面的pack和unpack函数进行读写。下面就自己写代码验证一下。

    >>> from struct import *
    >>> file = open(r"c:/debug.txt", "wb")
    >>> file.write(pack("idh", 12345, 67.89, 15))
    >>> file.close()

接着再将其读进来

    >>> file = open(r"c:/debug.txt", "rb")
    >>> (a,b,c) = unpack("idh",file.read(8+8+2))
    >>> a,b,c
    (12345, 67.890000000000001, 15)
    >>> print a,b,c
    12345 67.89 15
    >>> file.close()

在操作过程中需要注意数据的size

注意 wb,rb中的b字，一定不可以少

方法1：

    myfile=open('c:\\t','rb')
    s=myfile.read(1)
    byte=ord(s) #将一个字节 读成一个数
    print hex(byte) #转换成16进制的字符串

方法2

    import struct
    myfile=open('c:\\t','rb').read(1)
    print struct.unpack('c',myfile)
    print struct.unpack('b',myfile)

写入

To open a file for binary writing is easy, it is the same way you do for reading, just change the mode into "wb".
file = open("test.bin","wb")
But, how to write the binary byte into the file?
You may write it straight away with hex code like this:
file.write("\x5F\x9D\x3E") file.close()
Now, check it out with hexedit,
hexedit test.bin
You will see this:
00000000 5F 9D 3E _.> 00000020 00000040
Now, open the file to append more bytes:
file = open("test.bin","ab")
What if I want to store by bin value into a stream and write it one short?
s ="\x45\xF3" s = s + "%c%c" % (0x45,0xF3) file.write(s) file.close()
Any convenient ways if I can obtained a hex string, and want to convert it back to binary format?
Yes, you just need to import binascii
import binascii hs="5B7F888489FEDA" hb=binascii.a2b_hex(hs) file.write(hb) file.close()

希望本文所述对大家的Python程序设计有所帮助。