Type Punning Solution

NBTTag& TagFloat::read(std::istream& stream) {

    static_assert(
        sizeof(int32_t)==sizeof(float),
        "Sizes of types are not appropriate!"
    );

    union {
        int32_t tmp;
        float flt;
    };

    stream.read(
        reinterpret_cast<char *>(&tmp),
        sizeof(int32_t)
    );

    tmp=be32toh(tmp);

    payload=flt;

    return *this;

}