C++ 将数据写出压缩文件

要将数据写入压缩文件，可以使用zlib库中提供的函数。下面是一个简单的示例，展示如何使用C++编写数据并将其压缩并写入文件中：

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

const int CHUNK_SIZE = 16384; // 压缩块大小

void compressData(const char* data, size_t dataSize, const std::string& fileName)
{
    std::ofstream outFile(fileName, std::ios::out | std::ios::binary);
    if (!outFile.is_open())
    {
        std::cerr << "Error: Failed to open file " << fileName << " for writing!" << std::endl;
        return;
    }

    z_stream stream;
    stream.zalloc = Z_NULL;
    stream.zfree = Z_NULL;
    stream.opaque = Z_NULL;
    stream.avail_in = (uInt)dataSize;
    stream.next_in = (Bytef*)data;

    if (deflateInit(&stream, Z_DEFAULT_COMPRESSION) != Z_OK)
    {
        std::cerr << "Error: Failed to initialize compression stream!" << std::endl;
        return;
    }

    int ret;
    char outBuffer[CHUNK_SIZE];
    do
    {
        stream.avail_out = CHUNK_SIZE;
        stream.next_out = (Bytef*)outBuffer;

        ret = deflate(&stream, Z_FINISH);
        if (outFile.fail())
        {
            std::cerr << "Error: Failed to write compressed data to file!" << std::endl;
            deflateEnd(&stream);
            return;
        }

        size_t compressedSize = CHUNK_SIZE - stream.avail_out;
        outFile.write(outBuffer, compressedSize);
    } while (stream.avail_out == 0);

    deflateEnd(&stream);
    outFile.close();
    std::cout << "Data compressed and written to file " << fileName << std::endl;
}

在上面的示例中，我们使用了zlib库中的`deflate()`函数将数据压缩，并使用`deflateInit()`和`deflateEnd()`函数初始化和结束压缩流。我们使用`std::ofstream`类将压缩后的数据写入文件中。

需要注意的是，压缩后的数据是以二进制格式写入文件的，因此在读取时也需要以二进制格式进行读取。