使用zlib压缩/解压文件

压缩算法有很多，关于各类算法的开源库也不少，本文对zlib压缩算法的基本概念和用法作简要介绍。
代码如下：

string compressfile(string &str)
{
    string strcom;
    uLong srclen = str.length();
    char *buf;
    uLong buflen = compressBound(srclen);
    buf = new char[buflen];
    if (compress((Bytef*)buf, &buflen, (Bytef*)str.c_str(),srclen) == Z_OK)
    {
        strcom.assign(buf, buflen); 
    }

    delete[]buf;
    return strcom;
}

string uncompressfile(string &str)
{
    string struncom;
    uLong strlen = str.length();
    char *buf;
    uLong buflen = strlen * 10;
    buf = new char[buflen];
    if (uncompress((Bytef*)buf, &buflen, (Bytef*)str.c_str(), strlen) == Z_OK)
    {
        struncom.assign(buf,buflen);
    }

    delete[]buf;
    return struncom;
}

int main()
{
    /*获取原始数据*/
    string strsrc("This is test string！");
    cout << "strsrc is : " << strsrc << "; length is : " << strsrc.length() << endl;
    /*压缩后的数据，查看是乱码*/
    string strcom = compressfile(strsrc);
    cout << "strcom is : " << strcom << "; length is : " << strcom.length() << endl;
    /*解压后的数据，应与元数据一致*/
    string struncom = uncompressfile(strcom);
    cout << "struncom is : " << struncom << "; length is : " << struncom.length() << endl;

    return 0;
}

Linux环境下编译命令：

g++ -g -W -o test test.cpp -lz

输出结果：

（细心的读者可能会发现压缩后的字符串反而边长了，为什么呢？换一个长一点的源字符串试一试呢？）