Question

我的项目中有两个职能,将一个特性阵列改为一个基本类型(播种-草),另一个是围绕(uncast_type)。

They are ugly and rely on underlying assumptions in the C++ compiler. Is there anything in std or boost that I can replace these with?

typedef uint8_t byte;
typedef std::vector<byte> data_chunk;

template<typename T>
T cast_chunk(data_chunk chunk, bool reverse=false)
{
    #ifdef BOOST_LITTLE_ENDIAN
        // do nothing
    #elif BOOST_BIG_ENDIAN
        reverse = !reverse;
    #else
        #error "Endian isn t defined!"
    #endif

    if (reverse)
        std::reverse(begin(chunk), end(chunk));

    T val = 0;
    for (size_t i = 0; i < sizeof(T) && i < chunk.size(); ++i)
        val += static_cast<T>(chunk[i]) << (i*8);
    return val;
}

template<typename T>
data_chunk uncast_type(T val, bool reverse=false)
{
    #ifdef BOOST_LITTLE_ENDIAN
        // do nothing
    #elif BOOST_BIG_ENDIAN
        reverse = !reverse;
    #else
        #error "Endian isn t defined!"
    #endif

    data_chunk chunk;
    for (size_t i = 0; i < sizeof(T); ++i)
        chunk.push_back(reinterpret_cast<byte*>(&val)[i]);

    if (reverse)
        std::reverse(begin(chunk), end(chunk));
    return chunk;
}

通常如何使用:

uint64_t val = 110;
data_chunk byte_array = uncast_type(val);
assert(val == cast_chunk<uint64_t>(byte_array);

增编

Answer 1

增强能力:国家图书馆提供conversion职能和 rel=“nofollow” 型,具体内容是:。

这四项职能与你的工作最相似:

template <class T> void native_to_big(T& x);
template <class T> void native_to_little(T& x);
template <class T> void big_to_native(T& x);
template <class T> void little_to_native(T& x);

template <class T> void native_to_big(T source, T& target);
template <class T> void native_to_little(T source, T& target);
template <class T> void big_to_native(T source, T& target);
template <class T> void little_to_native(T source, T& target);

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