Solved: Writing wstring to text file

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MACCONSUELA

Writing wstring to text file

I tried writing a wstring to a text file, but I keep getting a text file that has single byte charactors instead of a wchar?
Can someone please provide example code.

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jkr 🇩🇪

#include <string>
using namespace std;
void main () {
wstring wstr = L"This is UNICODE";
wofstream wofs ( "myfile.txt");
wofs << wstr << endl;
actually should do it....

MACCONSUELA

ASKER

That's what I tried in the first place, but it didn't work.
The text file I get has single byte charactors.

jkr 🇩🇪

>>The text file I get has single byte charactors.
Err, how do you know? most editors will display the text as readable chars? Hex editors will show you the 'real' content.

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MACCONSUELA

ASKER

I used VC++, and opened it as a binary file.

MACCONSUELA

ASKER

Just incase, I copied your code and pasted in a new VC++ project.
#include <string>
#include <iostream>
#include <fstream>
using namespace std;
int main(int argc, char* argv[])
wstring wstr = L"This is UNICODE";
wofstream wofs ( "c:\\myfile.txt");
wofs << wstr << endl;
return 0;
I ran the above program, and I still ended up with a single byte charactor text file.
I verified this by opening the file with VC++ in BINARY mode.
I also checked the file via explore, and view the property of the file. It showed the file as having 17 bytes.
If it was a UNICODE, it would be double that size.
jkr, have you tried this code on your computer? If so, what did you get.

MACCONSUELA

ASKER

By the way, I tried this out on a Windows 2000 and Windows 98.
I compiled it in VC++ version 6.0.
The code failed to work in both operating systems.

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fl0yd

That's really strange... I also tried to get it to work on my win2k-system with vs6sp5. I can't get the src to compile to begin with; vc is complaining about the <<-operator not being defined for a std::wstring. So I kicked the std::wstring and placed the string-literal right in that place. I #undefine'd _MBCS (multi-byte-character-set) , #define'd _UNICODE and even UNICODE even though this shouldn't be necessary. To no avail - all I get is single-byte characters in the output-file. I also know for *SURE* they are single characters.

DanRollins 🇺🇸

As long as wifstream can read themn back, it seems that the standard allows wofstream to write 80bit values:
http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&oe=UTF8&th=ab095398862f62b2&rnum=12
So the question remains: How does one write 16-bit values to the file?
Well, as with all STL problems there is a very easy solution. It is as obvious as the nose on your face. All you need to do is single-step through the code to find that the STL geniuses determine the size of the output character based upon the character attributes of the active locale. A locale is a very simple object, like they cover in DP 101 when they teach you about punchcards and all that. Sheesh. I goes without SAYING!
Here is the simple solution:
#include <locale>
#include <fstream>
using namespace std;
typedef codecvt<wchar_t, char, mbstate_t> Mybase;
// CLASS Simple_codecvt
class Simple_codecvt : public Mybase {
public:
typedef wchar_t _E;
typedef char _To;
typedef mbstate_t _St;
explicit Simple_codecvt(size_t _R = 0)
: Mybase(_R) {}
protected:
virtual result do_in(_St& _State,
const _To *_F1, const _To *_L1, const _To *& _Mid1,_E *_F2, _E *_L2, _E *& _Mid2) const
{return (noconv); }
virtual result do_out(_St& _State, const _E *_F1, const _E *_L1, const _E *& _Mid1,_To *_F2, _To *_L2, _To *& _Mid2) const
{return (noconv); }
virtual result do_unshift(_St& _State,_To *_F2, _To *_L2, _To *& _Mid2) const
{return (noconv); }
virtual int do_length(_St& _State, const _To *_F1,const _To *_L1, size_t _N2) const _THROW0()
{return (_N2 < (size_t)(_L1 - _F1)? _N2 : _L1 - _F1); }
virtual bool do_always_noconv() const _THROW0(){return (true); }
virtual int do_max_length() const _THROW0(){return (2); }
virtual int do_encoding() const _THROW0(){return (2); }
void main()
wstring wstr = L"This is UNICODE";
locale loc = _ADDFAC(locale::classic(), new Simple_codecvt);
wofstream wofs;
wofs.imbue(loc);
wofs.open( "c:\\temp\\myfile.bin", ios_base::out | ios_base::trunc | ios_base::binary);
wofs << wstr << endl;
=-=-=-=-=-=-=-
-- Dan
P.S. I know that most programmer types are too literal to understand sarcasm, so to the above description, please add:

DanRollins 🇺🇸

P.S. THe above code was cribbed from
http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&oe=UTF8&selm=3b82680f%240%2423296%40wodc7nh0.news.uu.net&rnum=9
which cribbed it from:
P.J. Plauger, ``Standard C/C++: Unicode Files,'' C/C++ Users Journal,April 1999.

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ASKER CERTIFIED SOLUTION

Axter 🇺🇸

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DanRollins 🇺🇸

Axter is correct. The original question is about how to write a wide-character string to the file and that solution should work. The stuff about wofstream is a side issue.
-- Dan

rstaveley 🇬🇧

This is really a plea to DanRollins....
Please could you take a look at http:/Q_20797258.html#9747020 and tell me if you know why my attempt to implement your cribbed suggestion didn't work?
I appreciate that Axter has a working solution for this, doing binary writes, but I'd really like to see how it can be done with codecvt.

rstaveley 🇬🇧

Actually, looking at Axter's response (all these many moons later and with the benefit of more modern copilers), I see that his approach gets UTF-32 UNICODE on GCC 3.2 and UTF-16 UNICODE on VC 7.1, which is a reflection of the respective wchar_t implementations. That is exacltly what MACCONSUELA asked for of course.
But aren't you supposed to have a wchar_t('\0') at the beginning of the file for it to be valid UNICODE.... or is that just a convention for UTF-16 XML?
--------8<--------
#include <iostream>
#include <fstream>
#include <string>
int main()
using std::ios;
std::wstring wstr = L"abc";
std::ofstream ofs;