ANSI、UNICODE、UTF-8编码格式相互之间转换

#include <stdio.h>
#include <windows.h>
#include <locale.h>
#define BUFF_SIZE 1024

/*ANSI转换到Unicode*/
wchar_t * ANSIToUnicode( const char* str )
{
int textlen ;
wchar_t * result;
textlen = MultiByteToWideChar( CP_ACP, 0, str,-1, NULL,0 );
result = (wchar_t *)malloc((textlen+1)*sizeof(wchar_t));
memset(result,0,(textlen+1)*sizeof(wchar_t));
MultiByteToWideChar(CP_ACP, 0,str,-1,(LPWSTR)result,textlen );
return result;
}

/*Unicode转换到ANSI*/
char * UnicodeToANSI( const wchar_t* str )
{
char* result;
int textlen;
textlen = WideCharToMultiByte( CP_ACP, 0, str, -1, NULL, 0, NULL, NULL );
result =(char *)malloc((textlen+1)*sizeof(char));
memset( result, 0, sizeof(char) * ( textlen + 1 ) );
WideCharToMultiByte( CP_ACP, 0, str, -1, result, textlen, NULL, NULL );
return result;
}

//UTF8转换到Unicode
wchar_t * UTF8ToUnicode( const char* str )
{
int textlen ;
wchar_t * result;
textlen = MultiByteToWideChar( CP_UTF8, 0, str,-1, NULL,0 );
result = (wchar_t *)malloc((textlen+1)*sizeof(wchar_t));
memset(result,0,(textlen+1)*sizeof(wchar_t));
MultiByteToWideChar(CP_UTF8, 0,str,-1,(LPWSTR)result,textlen );
return result;
}

//Unicode转换到UTF8
char * UnicodeToUTF8( const wchar_t* str )
{
char* result;
int textlen;
textlen = WideCharToMultiByte( CP_UTF8, 0, str, -1, NULL, 0, NULL, NULL );
result =(char *)malloc((textlen+1)*sizeof(char));
memset(result, 0, sizeof(char) * ( textlen + 1 ) );
WideCharToMultiByte( CP_UTF8, 0, str, -1, result, textlen, NULL, NULL );
return result;
}

//ANSI转换到UTF8
char* ANSIToUTF8(const char* str)
{
return UnicodeToUTF8(ANSIToUnicode(str));
}

//UTF8转换到ANSI
char* UTF8ToANSI(const char* str)
{
return UnicodeToANSI(UTF8ToUnicode(str));
}

/*宽字符转换为多字符Unicode - ANSI*/
char* w2m(const wchar_t* wcs)
{
int len;
char* buf;
len =wcstombs(NULL,wcs,0);
if (len == 0)
return NULL;
buf = (char *)malloc(sizeof(char)*(len+1));
memset(buf, 0, sizeof(char) *(len+1));
len =wcstombs(buf,wcs,len+1);
return buf;
}

/*多字符转换为宽字符ANSI - Unicode*/
wchar_t* m2w(const char* mbs)
{
int len;
wchar_t* buf;
len =mbstowcs(NULL,mbs,0);
if (len == 0)
return NULL;
buf = (wchar_t *)malloc(sizeof(wchar_t)*(len+1));
memset(buf, 0, sizeof(wchar_t) *(len+1));
len =mbstowcs(buf,mbs,len+1);
return buf;
}

int main()
{
/*使用wcstombs和mbstowcs之前必须调用setlocale，以便决定内码*/
setlocale(LC_ALL,".936");
/*假定有一个Unicode(UTF-16LE)编码的文件，将其打开，重新编码为ANSI
，写入aa.txt中，再继续编码回Unicode，写入aw.txt中*/
/*如果不存在a.txt文件，则程序出错，没有做错误处理*/
char* filename = "a.txt";
char* filenamea = "aa.txt";
char* filenamew = "aw.txt";
FILE*     input=fopen( filename, "rb");
FILE*     inputa=fopen( filenamea, "wb");
FILE*     inputw=fopen( filenamew, "wb");
wchar_t * buf ;
/*BOE设置，UTF-16LE的BOE为FEFF，如果不先将其读取出来，wcstombs会调用失败*/
fgetwc(input);
fputwc(0xFEFF,inputw);
/*开始读取文件*/
while(!feof(input))
{
buf = (wchar_t *)malloc(sizeof(wchar_t)*BUFF_SIZE)         ;
memset(buf,    0, sizeof(wchar_t) * BUFF_SIZE );
fgetws(buf,    BUFF_SIZE,    input);
fputs(w2m(buf),    inputa);
fputws(m2w(w2m(buf)),    inputw);
}
/*后续处理*/
fclose(input);
fclose(inputa);
fclose(inputw);
free(buf);

return 0;
}