GUID to std::string, std::string to GUID

GuidConverter.cpp

#ifndef _WIN32
typedef struct _GUID {
	uint32_t Data1;
	uint16_t Data2;
	uint16_t Data3;
	uint8_t Data4[8];
} GUID;
#endif

GUID StringToGuid(const std::string& str)
{
	GUID guid;
	sscanf(str.c_str(),
	       "{%8x-%4hx-%4hx-%2hhx%2hhx-%2hhx%2hhx%2hhx%2hhx%2hhx%2hhx}",
	       &guid.Data1, &guid.Data2, &guid.Data3,
	       &guid.Data4[0], &guid.Data4[1], &guid.Data4[2], &guid.Data4[3],
	       &guid.Data4[4], &guid.Data4[5], &guid.Data4[6], &guid.Data4[7] );

	return guid;
}

std::string GuidToString(GUID guid)
{
	char guid_cstr[39];
	snprintf(guid_cstr, sizeof(guid_cstr),
	         "{%08x-%04x-%04x-%02x%02x-%02x%02x%02x%02x%02x%02x}",
	         guid.Data1, guid.Data2, guid.Data3,
	         guid.Data4[0], guid.Data4[1], guid.Data4[2], guid.Data4[3],
	         guid.Data4[4], guid.Data4[5], guid.Data4[6], guid.Data4[7]);

	return std::string(guid_cstr);
}

Run-time Check Failure #2 - Stack around the "guid" was corrupted;
the code are as follow:
GUID YourCarAPI::StringToGuid(const std::string& str)
{

GUID guid;
sscanf(str.c_str(),

	"{%8x-%4hx-%4hx-%2hhx%2hhx-%2hhx%2hhx%2hhx%2hhx%2hhx%2hhx}",

	&guid.Data1, &guid.Data2, &guid.Data3,

	&guid.Data4[0], &guid.Data4[1], &guid.Data4[2], &guid.Data4[3],

	&guid.Data4[4], &guid.Data4[5], &guid.Data4[6], &guid.Data4[7] );

return guid;

}