如何在C中将单个位写入文件 [英] How to write single bits to a file in C

问题描述

我正在编程一个熵编码算法，我想把一个像编码字符的单个位写入一个文件。例如，我想写011到一个文件，但如果你将它存储为字符，它将占用3字节而不是3位。所以我的最后一个问题是：如何写一个文件的单位？

提前感谢

解决方案

您不能将单个位写入文件，分辨率为单个字节。

如果要写入位顺序，你必须批量，直到你有一个完整的字节，然后写。 Psuedo代码（虽然C样）将符合以下条件：

  currbyte = 0 
 bitcount = 0 
 def writeBit（bit）：
 currbyte = currbyte<<< 1 | bit 
 bitcount ++ 
如果bitcount == BITS_PER_BYTE：
将currbyte写入文件
 currbyte = 0 
 bitcount = 0 
  / pre> 
 
 
你想要更改个别位，你必须读取一个字节，使用bitwise操作操作它，然后写回。
 
I am programming an entropy coding algorithm and I want to write single bits like an encoded character to a file. For example I want to write 011 to a file but if you would store it as character it'd take up 3 Bytes instead of 3 Bits. So my final question is: How can I write single bits to a file?

Thanks in advance!
解决方案
You can't write individual bits to a file, the resolution is a single byte.

If you want to write bits in sequence, you have to batch them up until you have a full byte, then write that. Psuedo-code (though C-like) for that would be along the lines of:
currbyte = 0
bitcount = 0
def writeBit (bit):
    currbyte = currbyte << 1 | bit
    bitcount++
    if bitcount == BITS_PER_BYTE:
        write currbyte to file
        currbyte = 0
        bitcount = 0
Of you want to change individual bits, you have to read in a byte, use bitwise operations to manipulate it, then write it back.

                        
这篇关于如何在C中将单个位写入文件的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！