The Guid should be quicker, as the comparison is simpler – just a few direct bytes. The string involves a dereference and lots more work. Of course – you could profile ;-p Evidence: Searching for 7f9b349f-f36f-94de-ad96-04279ddf6ecf As guid: 466; -1018643328 As string: 512; -1018643328 Searching for 870ba465-08f2-c872-cfc9-b3cc1ffa09de As guid: 470; 1047183104 As string: 589; 1047183104 … Read more
If you can afford to use Boost, then there is a UUID library that should do the trick. It’s very straightforward to use – check the documentation and this answer.
You can try the following: function GUID() { if (function_exists(‘com_create_guid’) === true) { return trim(com_create_guid(), ‘{}’); } return sprintf(‘%04X%04X-%04X-%04X-%04X-%04X%04X%04X’, mt_rand(0, 65535), mt_rand(0, 65535), mt_rand(0, 65535), mt_rand(16384, 20479), mt_rand(32768, 49151), mt_rand(0, 65535), mt_rand(0, 65535), mt_rand(0, 65535)); } Source – com_create_guid
I think CoCreateGuid is what you’re after. Example: GUID gidReference; HRESULT hCreateGuid = CoCreateGuid( &gidReference );
The RFC explains it. It is a GUID, selected because it is “unlikely to be used by network endpoints that do not understand the WebSocket Protocol”. See RFC 6455. If you’re interested in the specifics of the format for GUIDs like that, see RFC 4122.
If you want be sure you need to check both SomeProperty == null || SomeProperty == Guid.Empty Because it can be null ‘Nullable’ and it can be an empty GUID something like this {00000000-0000-0000-0000-000000000000}
UUIDs/GUIDs are specified by RFC4122. Although Version 4 UUIDs are created from random numbers Section 6 makes an explicit statement on security: Do not assume that UUIDs are hard to guess; they should not be used as security capabilities (identifiers whose mere possession grants access), for example. A predictable random number source will exacerbate the … Read more
The Windows SDK comes with a tool called uuidgen (if you have Visual Studio, you’ll have the Windows SDK, and you need to run the Visual Studio Command Prompt to set proper paths). C:\>uuidgen This will output a new GUID, e.g. cc23b318-156e-473f-aa6e-517bf091a0f0
Technically, there are no “dashes” in a GUID. A GUID is a 128-bit value which is usually stored in the following manner (using C# here to represent the structure): public struct Guid { public ulong Data1; public ushort Data2; public ushort Data3; public fixed byte Data4[8]; } The dashes are in the string representation of … Read more
GUID vs.Sequential GUID A typical pattern it’s to use Guid as PK for tables, but, as referred in other discussions (see Advantages and disadvantages of GUID / UUID database keys) there are some performance issues. This is a typical Guid sequence f3818d69-2552-40b7-a403-01a6db4552f7 7ce31615-fafb-42c4-b317-40d21a6a3c60 94732fc7-768e-4cf2-9107-f0953f6795a5 Problems of this kind of data are:< – Wide distributions of … Read more