c++ - 将 cpp_int 类型导出到位时，boost::multiprecision::export_bits 丢失符号

Question

我将负号值导出到位并导回，但是当位导入符号丢失时。

typedef multiprecision::int512_t balance_value;
vector<uint8_t> byteSet;
export_bits(static_cast<boost::multiprecision::int512_t>(balance), back_inserter(byteSet), 8);

当我尝试将位导入回 int512_t 时，值的符号丢失了。

balance_value balance;
import_bits(balance, byteSet.begin(), byteSet.end());

Answer 1

这是设计使然。 documentation州

Exports the absolute value of val to OutputIterator out. The function will write chunk_size bits at a time to the OutputIterator, and if msv_first is true, will write the most-significant block first. Byte and bit order within each chunk_size block is always in the machines native format. Further, each block is stored in a boost::uintmax_t when it's assigned to *out.

如果您需要可移植的表示形式，还要注意字节顺序问题。