Not for zip packages?

[flaviu22]

"C++ lib for gzip compression and decompression" means not for zip packages?
I have tried:

	std::string filename("c:/transfer/test.zip");
	std::ifstream ifs(filename, std::ios_base::in | std::ios_base::binary);
	if (ifs.is_open())
	{
		std::cout << "zip opened\n";
		std::string str_compressed((std::istreambuf_iterator<char>(ifs.rdbuf())), std::istreambuf_iterator<char>());
		ifs.close();
		std::string out{};
		gzip::Decompressor decomp{};
		try
		{
			decomp.decompress(out, str_compressed.data(), str_compressed.size());
			std::cout << out.c_str() << std::endl;
		}
		catch (std::exception& ex)
		{
			std::cout << ex.what() << std::endl;
		}
	}

But I got:
incorrect header check
So, gzip isn't for zip packages?