中文字符串的编码转换(c实现)

    中文字符串在c/c++中表示为字节序列，在分词的时候需要根据不同的编码方式进行分词，一般分词器需要转换成统一的编码方式再进行转换，有些分词器如ICTCLAS在分词的时候可以不显示定义编码方式，可以检测字符串的编码方式再进行转换，本文就项目中用到的几种编码转换方式进行总结，主要利用了iconv进行编码转换。

const bchar_t zero[1] = {L'\0'};

void gbk_utf16le(char* inbuf, size_t inlen, char* outbuf)

{

iconv_t cd = iconv_open( "UTF-16LE//IGNORE", "GBK");

bzero( outbuf, inlen*4);

char *in = inbuf;

char *out = outbuf;

size_t outlen = inlen*4;

iconv(cd, &in, (size_t *)&inlen, &out,&outlen);

if( outlen>=sizeof(bchar_t) )

*((bchar_t *) out) = L'\0';

iconv_close(cd);

}

void utf16le_gbk(char* inbuf, size_t inlen, char* outbuf)

{

iconv_t cd = iconv_open( "GBK//IGNORE", "UTF-16LE");

bzero( outbuf, inlen*4);

char *in = inbuf;

char *out = outbuf;

size_t outlen = inlen*4;

iconv(cd, &in, (size_t *)&inlen, &out,&outlen);

if( outlen>=sizeof(char) )

*((char *) out) = '\0';

iconv_close(cd);

}

void utf16le_utf8(char* inbuf, size_t inlen, char* outbuf)

{

iconv_t cd = iconv_open( "UTF-8//IGNORE", "UTF-16LE");

bzero( outbuf, inlen*4);

char *in = inbuf;

char *out = outbuf;

size_t outlen = inlen*4;

iconv(cd, &in, (size_t *)&inlen, &out,&outlen);

if( outlen>=sizeof(char) )

*((char *) out) = '\0';

iconv_close(cd);

}

void gbk_utf16le(char* inbuf, size_t inlen, char* outbuf,uint32_t& outbuflen)

{

iconv_t cd = iconv_open( "UTF-16LE//IGNORE", "GBK");

bzero( outbuf, inlen*4);

char *in = inbuf;

char *out = outbuf;

size_t outlen = inlen*4;

outbuflen = outlen;

iconv(cd, &in, (size_t *)&inlen, &out,&outlen);

//outlen is bytes of outbuf not used

outbuflen -= outlen;

if( outlen>=sizeof(bchar_t) )

*((bchar_t *) out) = L'\0';

iconv_close(cd);

}

void utf8_gbk(char* inbuf, size_t inlen, char* outbuf)

{

iconv_t cd = iconv_open( "GBK//IGNORE", "UTF-8");

bzero( outbuf, inlen*4);

char *in = inbuf;

char *out = outbuf;

size_t outlen = inlen*4;

iconv(cd, &in, (size_t *)&inlen, &out,&outlen);

if( outlen>=sizeof(char) )

*((char *) out) = '\0';

iconv_close(cd);

}

/*将char类型转换为uint16类型，主要是将2个字节的char拼成1个16进制数*/

void ch_uint16(char* inbuf, int& inlen, uint16_t* outbuf, int& outlen)

{

char *in = inbuf;

uint16_t *out = outbuf;

int k = 0;

outlen = 0;

char temp[20];

memset(temp,0,20);

for(;k+2<=inlen;k+=2){

if( int(in[k]&0xFF) >15){

sprintf(temp,"%x%x",in[k+1]&0xFF ,in[k]&0xFF);}

else{

sprintf(temp,"%x%d%x",in[k+1]&0xFF,0,in[k]&0xFF);}

uint16_t ut;

sscanf(temp,"%x",&ut);

out[outlen] = ut ;

outlen++ ;

}

out[outlen] = L'\0';

}