zlib中基本函数都有哪些,相信很多没有经验的人对此束手无策,为此本文总结了问题出现的原因和解决方法,通过这篇文章希望你能解决这个问题。
获取版本函数:zlibVersion
压缩函数:deflateInit、deflate、deflateEnd
解压缩函数:inflateInit、inflate、inflateEnd
#include <iostream>
#include <string>
#include <zlib.h>
#include <zconf.h>
using namespace std;
#define CHUNK 16384
int def(FILE *source, FILE *dest, int level)
{
z_stream strm;
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
deflateInit(&strm, level);
int flush;
int have;
unsigned char in[CHUNK];
unsigned char out[CHUNK];
do
{
strm.avail_in = fread(in, 1, CHUNK, source);
strm.next_in = in;
flush = feof(source) ? Z_FINISH : Z_NO_FLUSH;
do
{
strm.avail_out = CHUNK;
strm.next_out = out;
deflate(&strm, flush);
have = CHUNK - strm.avail_out;
fwrite(out, 1, have, dest);
} while (0 == strm.avail_out);
} while (Z_FINISH != flush);
deflateEnd(&strm);
return Z_OK;
}
int inf(FILE *source, FILE *dest)
{
z_stream strm;
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
inflateInit(&strm);
int ret = Z_OK;
int have;
unsigned char in[CHUNK];
unsigned char out[CHUNK];
do
{
strm.avail_in = fread(in, 1, CHUNK, source);
strm.next_in = in;
if(0 == strm.avail_in)
break;
do
{
strm.avail_out = CHUNK;
strm.next_out = out;
ret = inflate(&strm, Z_NO_FLUSH);
have = CHUNK - strm.avail_out;
fwrite(out, 1, have, dest);
} while (0 == strm.avail_out);
} while (Z_STREAM_END != ret);
inflateEnd(&strm);
return Z_OK;
}
void main(int argc, char *argv[])
{
cout<<"zlibVersion:"<<zlibVersion()<<endl;
FILE *fp1 = fopen("1.txt","rb+");
FILE *fp2 = fopen("2.txt", "rb+");
FILE *fp3 = fopen("3.txt", "rb+");
if((NULL == fp3) || (NULL == fp3) || (NULL == fp3))
{
cout<<"fail to open file."<<endl;
return;
}
//压缩
def(fp1, fp2, Z_DEFAULT_COMPRESSION);
//解压缩,这个2个函数要分别调用。
inf(fp2, fp3);
}
此代码参数官网示例代码,本代码为了学习,只写了最简单的函数,没有错误处理。
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