在编写lz4 csv到压缩二进制文件转换器(大量外汇交易数据csv)的过程中,希望减少我的小vps上的存储/磁盘带宽需求。 自包含的代码来说明lz4压缩C++示例
#include <string>
#include <fstream>
#include <iostream>
#include "lz4.h"
using namespace std;
int main()
{
char szString[] = "2013-01-07 00:00:04,0.98644,0.98676 2013-01-07 00:01:19,0.98654,0.98676 2013-01-07 00:01:38,0.98644,0.98696";
const char* pchSource = szString;
int nInputSize = sizeof(szString);
cout <<"- pchSource -" << endl << pchSource << endl;
cout <<"nbytes = "<< nInputSize << endl << endl;
ofstream source("pchSource.txt");
source << pchSource;
int nbytesPassed = 0;
int nMaxCompressedSize = LZ4_compressBound(nInputSize);
char *pszDest = new char[nMaxCompressedSize];
nbytesPassed = LZ4_compress(pchSource, pszDest, nInputSize);
cout <<"- pszDest Compressed-" << endl;
cout <<"nbytesPassed = "<< nbytesPassed << endl;
cout << pszDest << endl << endl;
// pszDest garbage ?
char *pszDestUnCompressed = new char[nInputSize];
LZ4_uncompress(pszDest, pszDestUnCompressed, nInputSize);
cout <<"- pszDestUnCompressed -" << endl;
cout <<"nbytesPassed = "<< nbytesPassed << endl;
cout << pszDestUnCompressed << endl << endl;
//pszDestUnCompressed is correct ?
delete[] pszDestUnCompressed;
pszDestUnCompressed = 0;
// ok lets write compressed pszDest to pszDest.dat
ofstream outCompressedFile("pszDest.dat",std::ofstream::binary);
outCompressedFile.write (pszDest,nMaxCompressedSize);
delete[] pszDest;
pszDest = 0;
//read it back in and try to uncompress it
ifstream infile("pszDest.dat",std::ifstream::binary);
infile.seekg (0,infile.end);
int nCompressedInputSize = infile.tellg();
infile.seekg (0);
char* buffer = new char[nCompressedInputSize];
infile.read (buffer,nCompressedInputSize);
const char* pchbuffer = buffer;
char* pszUnCompressedFile = new char[nInputSize];
nbytesPassed = LZ4_uncompress(pchbuffer, pszUnCompressedFile, nInputSize);
cout <<"- pszUnCompressedFile -" << endl;
cout <<"nbytesPassed = "<< nbytesPassed << endl;
cout << pszUnCompressedFile << endl;
//write uncompressed pszDest.dat to pszUnCompressedFile.txt
ofstream outUncompressedSource("pszUnCompressedFile.txt");
outUncompressedSource << pszUnCompressedFile;
// On my system 32bit ArchLinux 3.7.10-1 - gcc 4.7.2-4
// file contains random Garbage
delete[] buffer;
buffer = 0;
delete[] pszUnCompressedFile;
pszUnCompressedFile = 0;
return 0;
}
CONSOLE OUTPUT :
- pchSource -
2013-01-07 00:00:04,0.98644 .....
nbytes = 108
- pszDest Compressed-
nbytesPassed = 63
�2013-01-07 00:
- pszDestUnCompressed -
nbytesPassed = 63
2013-01-07 00:00:04,0.98644 .....
- pszUnCompressedFile -
nbytesPassed = -17
�W��W�-07 q
Process returned 0 (0x0) execution time : 0.010 s
Press ENTER to continue.
我显然失去了一些东西,除了形成一个包括在源样本是否有任何-其他用途的例子吗?
啊是的,现在有道理,谢谢指针 – ArchNemSyS 2013-04-25 23:39:23