如果你有c++ 17，那么添加这个头文件

#include <algorithm>

使用这个模板函数交换字节:

template <typename T>
void swapEndian(T& buffer)
{
    static_assert(std::is_pod<T>::value, "swapEndian support POD type only");
    char* startIndex = static_cast<char*>((void*)buffer.data());
    char* endIndex = startIndex + sizeof(buffer);
    std::reverse(startIndex, endIndex);
}

这样称呼它:

swapEndian (stlContainer);

和在C中一样:

short big = 0xdead;
short little = (((big & 0xff)<<8) | ((big & 0xff00)>>8));

您还可以声明一个无符号字符的向量，将输入值memcpy放入其中，将字节反向转换为另一个向量，然后将字节memcpy取出，但这将花费比旋转位长几个数量级的时间，特别是对于64位值。

我们已经用模板做到了这一点。你可以这样做:

// Specialization for 2-byte types.
template<>
inline void endian_byte_swapper< 2 >(char* dest, char const* src)
{
    // Use bit manipulations instead of accessing individual bytes from memory, much faster.
    ushort* p_dest = reinterpret_cast< ushort* >(dest);
    ushort const* const p_src = reinterpret_cast< ushort const* >(src);
    *p_dest = (*p_src >> 8) | (*p_src << 8);
}

// Specialization for 4-byte types.
template<>
inline void endian_byte_swapper< 4 >(char* dest, char const* src)
{
    // Use bit manipulations instead of accessing individual bytes from memory, much faster.
    uint* p_dest = reinterpret_cast< uint* >(dest);
    uint const* const p_src = reinterpret_cast< uint const* >(src);
    *p_dest = (*p_src >> 24) | ((*p_src & 0x00ff0000) >> 8) | ((*p_src & 0x0000ff00) << 8) | (*p_src << 24);
}

void writeLittleEndianToBigEndian(void* ptrLittleEndian, void* ptrBigEndian , size_t bufLen )
{
    char *pchLittleEndian = (char*)ptrLittleEndian;

    char *pchBigEndian = (char*)ptrBigEndian;

    for ( size_t i = 0 ; i < bufLen ; i++ )    
        pchBigEndian[bufLen-1-i] = pchLittleEndian[i];
}

std::uint32_t row = 0x12345678;

char buf[4]; 

writeLittleEndianToBigEndian( &row, &buf, sizeof(row) );

我喜欢这个，只是为了风格:-)

long swap(long i) {
    char *c = (char *) &i;
    return * (long *) (char[]) {c[3], c[2], c[1], c[0] };
}

虽然没有使用固有函数有效，但肯定是可移植的。我的回答:

#include <cstdint>
#include <type_traits>

/**
 * Perform an endian swap of bytes against a templatized unsigned word.
 *
 * @tparam value_type The data type to perform the endian swap against.
 * @param value       The data value to swap.
 *
 * @return value_type The resulting swapped word.
 */
template <typename value_type>
constexpr inline auto endian_swap(value_type value) -> value_type
{
    using half_type = typename std::conditional<
        sizeof(value_type) == 8u,
        uint32_t,
        typename std::conditional<sizeof(value_type) == 4u, uint16_t, uint8_t>::
            type>::type;

    size_t const    half_bits  = sizeof(value_type) * 8u / 2u;
    half_type const upper_half = static_cast<half_type>(value >> half_bits);
    half_type const lower_half = static_cast<half_type>(value);

    if (sizeof(value_type) == 2u)
    {
        return (static_cast<value_type>(lower_half) << half_bits) | upper_half;
    }

    return ((static_cast<value_type>(endian_swap(lower_half)) << half_bits) |
            endian_swap(upper_half));
}