float uint32 uint16 转为uint8

appendUint32ToVec(std::vector & vec, unsigned int val,  bool bigEndian )
{
    if (bigEndian)
    {
//        unsigned char* p = (unsigned char*) &val;
//        p += 3;

//        vec.push_back(*p--);
//        vec.push_back(*p--);
//        vec.push_back(*p--);
//        vec.push_back(*p);
        uint8_t p = (val>>24)&0xFF;
        vec.push_back(p);
        p = (val>>16)&0xFF;
        vec.push_back(p);
        p = (val>>8)&0xFF;
        vec.push_back(p);
        p = (val&0xFF);
        vec.push_back(p);
    }
    else
    {
//        unsigned char* p = (unsigned char*) &val;
//        vec.push_back(*p++);
//        vec.push_back(*p++);
//        vec.push_back(*p++);
//        vec.push_back(*p++);
        uint8_t p = (val&0xFF);
        vec.push_back(p);
        p = (val>>8)&0xFF;
        vec.push_back(p);
        p = (val>>16)&0xFF;
        vec.push_back(p);
        p = (val>>24)&0xFF;
        vec.push_back(p);
    }
}

appendUint16ToVec(std::vector & vec, unsigned short val,  bool bigEndian )
{
    if (bigEndian)
    {
//        unsigned char* p = (unsigned char*) &val;
//        p += 1;

//        vec.push_back(*p--);
//        vec.push_back(*p);
        vec.push_back((val>>8)&0xFF);
        vec.push_back(val&0xFF);
    }
    else
    {
//        unsigned char* p = (unsigned char*) &val;
//        vec.push_back(*p++);
//        vec.push_back(*p++);
        vec.push_back(val&0xFF);
        vec.push_back((val>>8)&0xFF);

    }
}

appendFloadToVec(std::vector & vec, float val,  bool bigEndian)
{
    if (bigEndian)
    {

        unsigned char* p = (unsigned char*) &val;
        p+= 3;
        vec.push_back(*p--);
        vec.push_back(*p--);
        vec.push_back(*p--);
        vec.push_back(*p);
    }
    else
    {
        unsigned char* p = (unsigned char*) &val;
        vec.push_back(*p++);
        vec.push_back(*p++);
        vec.push_back(*p++);
        vec.push_back(*p++);
    }
}

float 也可以用结构体形式