wofstream输出unicode文件的问题
VS2008
std::wstring str = L"s";
std::wofstream ofile("F:\\test.txt");
ofile<<str;
为什么文件的内容是ss？似乎wofstream并没有输出unicode格式的流，而是把要输出的内容按ANSI输出了2遍。
另外wofstream的构造函数可以接受char的文件名也可以接受wchar_t的文件名，这两个有什么区别？
[解决办法]
这是因为输入输出流的缓冲区是char型的, 因此输出wchar_t就必须进行转换.
在"ofile <<str"; 使用 "单步调式", 你可以看到在写入文件之前, VC对str的内容进行了编码转换
如果想以unicode的格式输出, 在VC2008里可以使用以下方法
// unicode_basic_filebuf.cpp// compile with: /EHsc// ms-help://MS.MSDNQTR.v80.chs/MS.MSDN.v80/MS.VisualStudio.v80.chs/dv_vcstdlib/html/3196ba5c-bf38-41bd-9a95-70323ddfca1a.htm#include <iostream>#include <string>#include <fstream>#include <iomanip>#include <memory.h>#include <string.h>#define IBUFSIZE 16using namespace std;void hexdump(const string& filename);int main(){ wchar_t* wszHello = L"Hello World"; wchar_t wBuffer[128]; basic_filebuf<wchar_t> wOutFile; // Open a file, wcHello.txt, then write to it, then dump the // file's contents in hex wOutFile.open("wcHello.txt", ios_base::out | ios_base::trunc | ios_base::binary); if(!wOutFile.is_open()) { cout << "Error Opening wcHello.txt\n"; return -1; } wOutFile.sputn(wszHello, (streamsize)wcslen(wszHello)); wOutFile.close(); cout << "Hex Dump of wcHello.txt - note that output is ANSI chars:\n"; hexdump(string("wcHello.txt")); // Open a file, wwHello.txt, then set the internal buffer of // the basic_filebuf object to be of type wchar_t, then write // to the file and dump the file's contents in hex wOutFile.open("wwHello.txt", ios_base::out | ios_base::trunc | ios_base::binary); if(!wOutFile.is_open()) { cout << "Error Opening wwHello.txt\n"; return -1; } wOutFile.pubsetbuf(wBuffer, (streamsize)128); wOutFile.sputn(wszHello, (streamsize)wcslen(wszHello)); wOutFile.close(); cout << "\nHex Dump of wwHello.txt - note that output is wchar_t chars:\n"; hexdump(string("wwHello.txt")); return 0;}// dump contents of filename to stdout in hexvoid hexdump(const string& filename){ fstream ifile(filename.c_str(), ios_base::in | ios_base::binary); char *ibuff = new char[IBUFSIZE]; char *obuff = new char[(IBUFSIZE*2)+1]; int i; if(!ifile.is_open()) { cout << "Cannot Open " << filename.c_str() << " for reading\n"; return; } if(!ibuff || !obuff) { cout << "Cannot Allocate buffers\n"; ifile.close(); return; } while(!ifile.eof()) { memset(obuff,0,(IBUFSIZE*2)+1); memset(ibuff,0,IBUFSIZE); ifile.read(ibuff,IBUFSIZE); // corner case where file is exactly a multiple of // 16 bytes in length if(ibuff[0] == 0 && ifile.eof()) break; for(i = 0; i < IBUFSIZE; i++) { if(ibuff[i] >= ' ') obuff[i] = ibuff[i]; else obuff[i] = '.'; cout << setfill('0') << setw(2) << hex << (int)ibuff[i] << ' '; } cout << " " << obuff << endl; } ifile.close();}