C语言实现字节流与十六进制字符串的相互转换

void ByteToHexStr(const unsigned char* source, char* dest, int sourceLen)
{
short i;
unsigned char highByte, lowByte;

for (i = 0; i < sourceLen; i++)
{
highByte = source[i] >> 4;
lowByte = source[i] & 0x0f ;

highByte += 0x30;

if (highByte > 0x39)
dest[i * 2] = highByte + 0x07;
else
dest[i * 2] = highByte;

lowByte += 0x30;
if (lowByte > 0x39)
dest[i * 2 + 1] = lowByte + 0x07;
else
dest[i * 2 + 1] = lowByte;
}
return ;
}

//字节流转换为十六进制字符串的另一种实现方式
void Hex2Str( const char *sSrc,  char *sDest, int nSrcLen )
{
int  i;
char szTmp[3];

for( i = 0; i < nSrcLen; i++ )
{
sprintf( szTmp, "%02X", (unsigned char) sSrc[i] );
memcpy( &sDest[i * 2], szTmp, 2 );
}
return ;
}

//十六进制字符串转换为字节流
void HexStrToByte(const char* source, unsigned char* dest, int sourceLen)
{
short i;
unsigned char highByte, lowByte;

for (i = 0; i < sourceLen; i += 2)
{
highByte = toupper(source[i]);
lowByte  = toupper(source[i + 1]);

if (highByte > 0x39)
highByte -= 0x37;
else
highByte -= 0x30;

if (lowByte > 0x39)
lowByte -= 0x37;
else
lowByte -= 0x30;

dest[i / 2] = (highByte << 4) | lowByte;
}
return ;
}