C语言实现字节流与十六进制字符串的相互转换

//字节流转换为十六进制字符串  
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;
}

//string实现方法字节流转十六进制字符串
std::string ToHexString(const UCHAR* buf, int len, std::string tok/* = " "*/)
{
	std::string output;
	char temp[8];
	for (int i = 0; i < len; ++i)
	{
		sprintf(temp, "%.2x", (UCHAR)buf[i]);
		output.append(temp);
		if (i < len -1)
		{
			output.append(tok);
		}
	}

	return output;
}

//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;
}