Print a GUID variable

I have a GUID variable and I want to write inside a text file its value. GUID definition is:

typedef struct _GUID {          // size is 16
    DWORD Data1;
    WORD   Data2;
    WORD   Data3;
    BYTE  Data4[8];
} GUID;

But I want to write its value like:

CA04046D-0000-0000-0000-504944564944

I observed that:

• Data1 holds the decimal value for CA04046D
• Data2 holds the decimal value for 0
• Data3 holds the decimal value for next 0

But what about the others?

I have to interpret myself this values in order to get that output or is there a more direct me开发者_高级运维thod to print such a variable?

Use the StringFromCLSID function to convert it to a string

e.g.:

GUID guid;
CoCreateGuid(&guid);

OLECHAR* guidString;
StringFromCLSID(guid, &guidString);

// use guidString...

// ensure memory is freed
::CoTaskMemFree(guidString);

Also see the MSDN definition of a GUID for a description of data4, which is an array containing the last 8 bytes of the GUID

Sometimes its useful to roll your own. I liked fdioff's answer but its not quite right. There are 11 elements of different sizes.

printf("Guid = {%08lX-%04hX-%04hX-%02hhX%02hhX-%02hhX%02hhX%02hhX%02hhX%02hhX%02hhX}", 
  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]);

Output: "Guid = {44332211-1234-ABCD-EFEF-001122334455}"

Refer to Guiddef.h for the GUID layout.

Same, as a method:

void printf_guid(GUID guid) {
    printf("Guid = {%08lX-%04hX-%04hX-%02hhX%02hhX-%02hhX%02hhX%02hhX%02hhX%02hhX%02hhX}", 
      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]);
}

you can also pass a CLSID to this method.

You can eliminate the need for special string allocations/deallocations by using StringFromGUID2()

GUID guid = <some-guid>;
// note that OLECHAR is a typedef'd wchar_t
wchar_t szGUID[64] = {0};
StringFromGUID2(&guid, szGUID, 64);

In case you prefer C++ way

std::ostream& operator<<(std::ostream& os, REFGUID guid){

    os << std::uppercase;
    os.width(8);
    os << std::hex << guid.Data1 << '-';

    os.width(4);
    os << std::hex << guid.Data2 << '-';

    os.width(4);
    os << std::hex << guid.Data3 << '-';

    os.width(2);
    os << std::hex
        << static_cast<short>(guid.Data4[0])
        << static_cast<short>(guid.Data4[1])
        << '-'
        << static_cast<short>(guid.Data4[2])
        << static_cast<short>(guid.Data4[3])
        << static_cast<short>(guid.Data4[4])
        << static_cast<short>(guid.Data4[5])
        << static_cast<short>(guid.Data4[6])
        << static_cast<short>(guid.Data4[7]);
    os << std::nouppercase;
    return os;
}

Usage:

static const GUID guid = 
{ 0xf54f83c5, 0x9724, 0x41ba, { 0xbb, 0xdb, 0x69, 0x26, 0xf7, 0xbd, 0x68, 0x13 } };

std::cout << guid << std::endl;

Output:

F54F83C5-9724-41BA-BBDB-6926F7BD6813

In case when your code uses ATL/MFC you also could use CComBSTR::CComBSTR(REFGUID guid) from atlbase.h:

GUID guid = ...;
const CComBSTR guidBstr(guid);  // Converts from binary GUID to BSTR
const CString guidStr(guidBstr); // Converts from BSTR to appropriate string, ANSI or Wide

It will make conversion & memory cleanup automatically.

Inspired by JustinB's answer

#define GUID_FORMAT "%08lX-%04hX-%04hX-%02hhX%02hhX-%02hhX%02hhX%02hhX%02hhX%02hhX%02hhX"
#define GUID_ARG(guid) (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]

and then

printf("Int = %d, string = %s, GUID = {" GUID_FORMAT "}\n", myInt, myString, GUID_ARG(myGuid));

Courtesy of google's breakpad project:

std::string ToString(GUID *guid) {
    char guid_string[37]; // 32 hex chars + 4 hyphens + null terminator
    snprintf(
          guid_string, sizeof(guid_string),
          "%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 guid_string;
}

UUID guid = {0};
UuidCreate(&guid);
std::cout << ToString(&guid);

I know the question is quite old, but would this work maybe?

inline std::ostream& operator <<(std::ostream& ss,GUID const& item) {
  OLECHAR* bstrGuid;
  ::StringFromCLSID(item, &bstrGuid);
  ss << bstrGuid;
  ::CoTaskMemFree(bstrGuid);
  return ss;
}

Use UuidToString function to convert GUID to string. The function accepts UUID type which is typedef of GUID.

std::string
GuidToString(const GUID& guid, bool lower = false)
{
    const char* hexChars = lower ? "0123456789abcdef" : "0123456789ABCDEF";

    auto f = [hexChars](char* p, unsigned char v)
    {
        p[0] = hexChars[v >> 4];
        p[1] = hexChars[v & 0xf];
    };

    char s[36];
    f(s, static_cast<unsigned char>(guid.Data1 >> 24));
    f(s + 2, static_cast<unsigned char>(guid.Data1 >> 16));
    f(s + 4, static_cast<unsigned char>(guid.Data1 >> 8));
    f(s + 6, static_cast<unsigned char>(guid.Data1));
    s[8] = '-';
    f(s + 9, static_cast<unsigned char>(guid.Data2 >> 8));
    f(s + 11, static_cast<unsigned char>(guid.Data2));
    s[13] = '-';
    f(s + 14, static_cast<unsigned char>(guid.Data3 >> 8));
    f(s + 16, static_cast<unsigned char>(guid.Data3));
    s[18] = '-';
    f(s + 19, guid.Data4[0]);
    f(s + 21, guid.Data4[1]);
    s[23] = '-';
    f(s + 24, guid.Data4[2]);
    f(s + 26, guid.Data4[3]);
    f(s + 28, guid.Data4[4]);
    f(s + 30, guid.Data4[5]);
    f(s + 32, guid.Data4[6]);
    f(s + 34, guid.Data4[7]);

    return std::string(s, 36);
}

printf(%X-%X-%X-%X-%X", guid.Data1, guid.Data2, guid.Data3, &guid.Data4);