怎样把一个Unicode码的_Txt转换为ansi码的

本文提供了一种使用C++实现Unicode与Ansi编码相互转换的方法。通过具体的代码示例，详细介绍了如何从Unicode编码转换为Ansi编码，反之亦然。此方法适用于需要处理不同字符集的应用场景。

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1.Unicode编码的文件转换成Ansi文件更简单，每次读两个字节，
下面程序提供了双向转换，你只取Uniocde==>Ansi好了
#include "Sysutils.hpp"
void Ansi2Unicode(String f1,String f2) // Ansi===> Unicode
{
TStringList *ss=new TStringList;
ss->LoadFromFile(f1);
int fh=FileCreate(f2);
for (int i=0;i<ss->Count;i++)
{
String s0=ss->Strings[i];
s0=s0+"\r\n";
WideString ws=s0;
void *buf=(void *)ws.c_bstr();
FileWrite(fh,buf,ws.Length()*2);
}
FileClose(fh);
delete ss;
}
void Unicode2Ansi(String f1,String f2) // Unicode ==> Ansi
{
int fh1=FileOpen(f1,fmOpenRead);
int fh2=FileCreate(f2);
wchar_t w;
void *buf=(void *)&w;
while (true)
{
int l=FileRead(fh1,buf,2); // 每次读两个字节
if (l<2)
break;
AnsiString s=WideString(w);
FileWrite(fh2,(void *)s.c_str(),s.Length());
}
FileClose(fh1);
FileClose(fh2);
}
void __fastcall TForm1::Button1Click(TObject *Sender)
{
Ansi2Unicode("c:\\test1.txt","c:\\test2.txt");
ShowMessage("Finished");
}

void __fastcall TForm1::Button2Click(TObject *Sender)
{
Unicode2Ansi("c:\\test2.txt","c:\\test3.txt");
ShowMessage("Finished");
}

2.

int WideCharToMultiByte(

    UINT CodePage,	// code page 
    DWORD dwFlags,	// performance and mapping flags 
    LPCWSTR lpWideCharStr,	// address of wide-character string 
    int cchWideChar,	// number of characters in string 
    LPSTR lpMultiByteStr,	// address of buffer for new string 
    int cchMultiByte,	// size of buffer 
    LPCSTR lpDefaultChar,	// address of default for unmappable characters  
    LPBOOL lpUsedDefaultChar 	// address of flag set when default char. used 
   );