高效C++解壓方法分享

在C++中，有多種高效的方法可以用于解壓縮數據

1. 使用std::istream和std::ostream進行解壓縮：

#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>
#include <iterator>
#include <zlib.h>

std::vector<char> decompress(const std::vector<char>& compressedData) {
    z_stream zs;
    zs.zalloc = Z_NULL;
    zs.zfree = Z_NULL;
    zs.opaque = Z_NULL;
    zs.avail_in = compressedData.size();
    zs.next_in = reinterpret_cast<Bytef*>(compressedData.data());

    std::vector<char> decompressedData;
    char buffer[32768];
    do {
        zs.avail_out = sizeof(buffer);
        zs.next_out = reinterpret_cast<Bytef*>(buffer);

        int ret = inflate(&zs, Z_NO_FLUSH);
        if (ret != Z_OK && ret != Z_STREAM_END) {
            throw std::runtime_error("Decompression failed");
        }

        size_t have = sizeof(buffer) - zs.avail_out;
        decompressedData.insert(decompressedData.end(), buffer, buffer + have);
    } while (zs.avail_out == 0);

    inflateEnd(&zs);
    return decompressedData;
}

2. 使用第三方庫zlib進行解壓縮：

首先，需要安裝zlib庫并將其包含在項目中。然后，可以使用以下代碼進行解壓縮：

#include <iostream>
#include <fstream>
#include <vector>
#include <zlib.h>

std::vector<char> decompress(const std::vector<char>& compressedData) {
    z_stream zs;
    zs.zalloc = Z_NULL;
    zs.zfree = Z_NULL;
    zs.opaque = Z_NULL;
    zs.avail_in = compressedData.size();
    zs.next_in = reinterpret_cast<Bytef*>(compressedData.data());

    std::vector<char> decompressedData;
    char buffer[32768];
    do {
        zs.avail_out = sizeof(buffer);
        zs.next_out = reinterpret_cast<Bytef*>(buffer);

        int ret = inflate(&zs, Z_NO_FLUSH);
        if (ret != Z_OK && ret != Z_STREAM_END) {
            throw std::runtime_error("Decompression failed");
        }

        size_t have = sizeof(buffer) - zs.avail_out;
        decompressedData.insert(decompressedData.end(), buffer, buffer + have);
    } while (zs.avail_out == 0);

    inflateEnd(&zs);
    return decompressedData;
}

3. 使用第三方庫boost.iostreams進行解壓縮：

首先，需要安裝boost庫并將其包含在項目中。然后，可以使用以下代碼進行解壓縮：

#include <iostream>
#include <fstream>
#include <vector>
#include <boost/iostreams/filtering_stream.hpp>
#include <boost/iostreams/copy.hpp>
#include <boost/iostreams/filter/gzip.hpp>

std::vector<char> decompress(const std::vector<char>& compressedData) {
    std::vector<char> decompressedData;
    boost::iostreams::filtering_streambuf<boost::iostreams::input> in;
    in.push(boost::iostreams::gzip_decompressor());
    in.push(boost::iostreams::input(compressedData.data(), compressedData.size()));

    boost::iostreams::copy(in, std::back_inserter(decompressedData));
    return decompressedData;
}

這些方法都可以用于解壓縮數據，具體選擇哪種方法取決于你的需求和項目結構。