Question

我正在尝试使用std::basic_ofstream<std::uint8_t>将一些二进制数据写入文件，但是它在__check_facet（）处抛出了bad_cast。我想我应该以{{1}}的语言环境来imbue()，但我真的不知道该怎么做。我的动机是我想将写入二进制数据（std :: uint8_t版本）的流运算符与写入文本数据（char）的运算符区分开。

当std::codecvt<std::uint8_t, char, std::mbstate_t>调用write时失败，并且它具有空指针，因此抛出__check_facet()。

bad_cast

(gdb) l
45    template<typename _Facet>
46      inline const _Facet&
47      __check_facet(const _Facet* __f)
48      {
49        if (!__f)
50           __throw_bad_cast();
51        return *__f;
52      }

#0  std::__check_facet<std::codecvt<unsigned char, char, __mbstate_t> > (__f=0x0) at /usr/include/c++/7/bits/basic_ios.h:50
#1  0x000055555555a1c0 in std::basic_filebuf<unsigned char, std::char_traits<unsigned char> >::xsputn (this=0x7fffffffdc38, __s=0x7fffffffdc2f "*X\311uUUU", __n=1)
    at /usr/include/c++/7/bits/fstream.tcc:731
#2  0x0000555555557301 in std::basic_streambuf<unsigned char, std::char_traits<unsigned char> >::sputn (this=0x7fffffffdc38, __s=0x7fffffffdc2f "*X\311uUUU", __n=1) at /usr/include/c++/7/streambuf:451
#3  0x000055555555693c in std::basic_ostream<unsigned char, std::char_traits<unsigned char> >::_M_write (this=0x7fffffffdc30, __s=0x7fffffffdc2f "*X\311uUUU", __n=1) at /usr/include/c++/7/ostream:313
#4  0x00005555555560b0 in std::basic_ostream<unsigned char, std::char_traits<unsigned char> >::write (this=0x7fffffffdc30, __s=0x7fffffffdc2f "*X\311uUUU", __n=1)
    at /usr/include/c++/7/bits/ostream.tcc:196
#5  0x0000555555555cb1 in main () at test.cpp:7

该问题仅出现在具有g ++（当前使用7.3.0）的Linux上，在具有msvc的Windows上正常运行。

编辑：

最后，我想为二进制和文本输出实现单独的重载流运算符。像这样：

#include <fstream>

int main()
{
    std::basic_ofstream<std::uint8_t> ofs("test.bin", std::ios_base::out | std::ios_base::binary);
    std::uint8_t x = 42;
    ofs.write(&x, 1);
    ofs.close();
}

谢谢！

std :: basic_ofstream <std :: uint8_t>在__check_facet（）处写入失败

0 个答案: