文件压缩来处理c ++中的中间输出 [英] file compression to handle intermediary output in c++

问题描述

解决方案

我想压缩程序的中间输出（在C ++中） Boost IOStreams压缩您的数据，例如沿着这些行压缩/解压缩到/从文件（例如改编自批准文档）：

  #include< fstream& 
 #include< iostream> 
 
 #include< boost / iostreams / filtering_stream.hpp> 
 #include< boost / iostreams / filtering_streambuf.hpp> 
 #include< boost / iostreams / copy.hpp> 
 #include< boost / iostreams / filter / gzip.hpp> 
 
命名空间bo = boost :: iostreams; 
 
 int main（）
 {
 {
 std :: ofstream ofile（hello.gz，std :: ios_base :: out | std :: ios_base :: binary）; 
 bo :: filtering_ostream out; 
 out.push（bo :: gzip_compressor（））; 
 out.push（ofile）; 
 out<< 这是一个gz file\\\
; 
} 
 
 {
 std :: ifstream ifile（hello.gz，std :: ios_base :: in | std :: ios_base :: binary）; 
 bo :: filtering_streambuf< bo :: input>在; 
 in.push（bo :: gzip_decompressor（））; 
 in.push（ifile）; 
 boost :: iostreams :: copy（in，std :: cout）; 
} 
} 
  

您还可以看看Boost序列化可以使保存您的数据更容易。可以组合这两种方法（示例）。 IOStreams也支持 bzip 压缩。

编辑你可以压缩一个现有的文件...但它最好写为压缩开始。如果你真的想要，你可以调整下面的代码：

  std :: ifstream ifile（file，std :: ios_base :: in | std :: ios_base :: binary）; 
 std :: ofstream ofile（file.gz，std :: ios_base :: out | std :: ios_base :: binary）; 
 
 bo :: filtering_streambuf< bo :: output>出口; 
 out.push（bo :: gzip_compressor（））; 
 out.push（ofile）; 
 bo :: copy（ifile，out）; 
  

I want to compress a intermediate output of my program ( in C++) and then decompress it.

解决方案

You can use Boost IOStreams to compress your data, for example something along these lines to compress/decompresses into/from a file (example adapted from Boost docs):

#include <fstream>
#include <iostream>

#include <boost/iostreams/filtering_stream.hpp>    
#include <boost/iostreams/filtering_streambuf.hpp>
#include <boost/iostreams/copy.hpp>
#include <boost/iostreams/filter/gzip.hpp>

namespace bo = boost::iostreams;

int main() 
{
    {
    std::ofstream ofile("hello.gz", std::ios_base::out | std::ios_base::binary);
    bo::filtering_ostream out;
    out.push(bo::gzip_compressor()); 
    out.push(ofile); 
    out << "This is a gz file\n";
    }

    {
    std::ifstream ifile("hello.gz", std::ios_base::in | std::ios_base::binary);
    bo::filtering_streambuf<bo::input> in;
    in.push(bo::gzip_decompressor());
    in.push(ifile);
    boost::iostreams::copy(in, std::cout);
    }
}

You can also have a look at Boost Serialization - which can make saving your data much easier. It is possible to combine the two approaches (example). IOStreams support bzip compression as well.

EDIT: To address your last comment - you can compress an existing file... but it would be better to write it as compressed to begin with. If you really want, you could tweak the following code:

std::ifstream ifile("file", std::ios_base::in | std::ios_base::binary);
std::ofstream ofile("file.gz", std::ios_base::out | std::ios_base::binary);

bo::filtering_streambuf<bo::output> out;
out.push(bo::gzip_compressor());
out.push(ofile); 
bo::copy(ifile, out);

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