使用7zip的SDK

最新推荐文章于 2025-11-18 09:20:42 发布

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#7zip #delete #ios #float #算法 #input

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本文介绍了如何使用7zip的SDK进行数据压缩和解压缩操作。首先从官方下载SDK源代码，选取必要的lzma算法相关文件并加入工程。接着在C++程序中调用LzmaCompress和LzmaUncompress函数进行压缩和解压缩，并展示了时间消耗的计算方法。最后，程序将压缩和解压缩后的数据写入文件。

一去http://www.7-zip.org/sdk.html下载源代码，目前的版本是9.20

二把包解压之后有个C目录，把下面的Alloc.c，Alloc.h，LzFind.c，LzFind.h，LzFindMt.c，LzFindMt.h，LzHash.h，LzmaDec.c，LzmaDec.h，LzmaEnc.c，LzmaEnc.h，LzmaLib.c，LzmaLib.h，Threads.c，Threads.h，Types.h拷贝出来，这些是使用lzma算法编解码的必须文件，如果想要其他算法再拷其他文件。

三把上述文件加入工程，并在测试文件中包含LzmaLib.h，就可以种其中的函数了

#include <iostream>
#include <fstream>
#include <time.h>
#include <windows.h>
using namespace std;

#include "lzmalib.h"

int main(int argc, char* argv[])
{
size_t insize = 0;
size_t outsize = 0;
unsigned char * inbuf = 0;
unsigned char * outbuf = 0;
unsigned char * destbuf = 0;

if(argc == 1)
{
cout<<"please input infile"<<endl;
return -1;
}

ifstream infile;
cout<<argv[1]<<endl;
infile.open (argv[1], ios::binary );
//infile.open ("stocktrace.dat", ios::binary );

// get length of file:
infile.seekg (0, ios::end);
insize = infile.tellg();
infile.seekg (0, ios::beg);

// allocate memory:
inbuf = new unsigned char [insize];

// read data as a block:
infile.read ((char *)inbuf,insize);
infile.close();

unsigned propsSize = LZMA_PROPS_SIZE;
outsize = insize;
outbuf = new unsigned char [outsize];
LARGE_INTEGER t1,t2,feq;
QueryPerformanceFrequency(&feq);//每秒跳动次数
QueryPerformanceCounter(&t1);//测前跳动次数
//unsigned long start_tick = GetTickCount();//精确到毫秒

int res = LzmaCompress(
    &outbuf[LZMA_PROPS_SIZE], &outsize,
    &inbuf[0], insize,
    &outbuf[0], &propsSize,
    0, 1<<14, -1, -1, -1, 5, -1);

//unsigned long end_tick = GetTickCount();

QueryPerformanceCounter(&t2);//测后跳动次数
double d=((double)t2.QuadPart-(double)t1.QuadPart)/((double)feq.QuadPart);//时间差秒,*1000000就是微妙

cout<<"compress time is "<< d*1000000<<endl;

ofstream outfile;
outfile.open ("lzma.test", ios::binary );
outfile.write((char *)outbuf,outsize+LZMA_PROPS_SIZE);
outfile.close();

cout<<"insize is "<<insize <<" outsize is "<<outsize+LZMA_PROPS_SIZE<<" compress ratio is "<<((float)(outsize+LZMA_PROPS_SIZE)/(float)insize)<<endl;

//cout<<"return value is "<<res<<" encode time is "<<end_tick - start_tick<<" ms"<<endl;

size_t destlen = 2*insize;
destbuf = new unsigned char [destlen];
outsize = outsize;

// end_tick = GetTickCount();
QueryPerformanceFrequency(&feq);//每秒跳动次数
QueryPerformanceCounter(&t1);//测前跳动次数

res = LzmaUncompress(&destbuf[0], &destlen, &outbuf[LZMA_PROPS_SIZE], &outsize,
&outbuf[0], LZMA_PROPS_SIZE);

QueryPerformanceCounter(&t2);//测后跳动次数
d=((double)t2.QuadPart-(double)t1.QuadPart)/((double)feq.QuadPart);//时间差秒

//unsigned long last_tick = GetTickCount();