reading a UTF-16 file in Linux - c++

Question

I have the following program which reads a file into a string buffer.
#include <fstream>
#include <iostream>
#include <string>
using namespace std;
constexpr int BUFSIZE = 1024;
int main(int argc, char *argv[])
{
std::ifstream ifs(argv[1], std::ifstream::binary);
if(!ifs)
return 1;
string buffer(BUFSIZE, L'\0');
ifs.read(&buffer[0], BUFSIZE);
cerr << ifs.gcount() << endl;
return 0;
}
It prints out the expected 1024.
The following program which is supposed to read into a wstring buffer doesn't work though.
#include <fstream>
#include <iostream>
#include <string>
using namespace std;
constexpr int BUFSIZE = 1024;
int main(int argc, char *argv[])
{
std::wifstream ifs(argv[1], std::ifstream::binary);
if(!ifs)
return 1;
wstring buffer(BUFSIZE, L'\0');
ifs.read(&buffer[0], BUFSIZE);
cerr << ifs.gcount() << endl;
return 0;
}
Ir prints out 0 with the same file.
As you can see the only difference is changing the stream to a wstream and the buffer to a wstring.
I've tried both g++ 8.2.1 and clang++ 6.0.1 under OpenSUSE Tumbleweed.
Where is the problem/my error?

Answer 1

You should be using std::basic_ifstream<char16_t> and std::u16string for UTF-16. std::wifstream and std::wstring are not appropriate because the width of wchar_t is implementation defined. In Linux in particular, it is (usually?) 32 bits wide.
Same for character literals. You should use u'\0' etc. instead of L'\0'.