Why this code is everytime generating 0000-0000 as guid?

Question

 static int Main(string[] args)
        {
            Guid obj = new Guid();
            Console.WriteLine("New Guid is " + obj.ToString());
            Console.ReadLine();

        }

Because it is a constructor of a structure not a GUID generator — Callum Linington, Dec 15 '14 at 08:45
http://msdn.microsoft.com/en-us/library/system.guid.newguid(v=vs.110).aspx — Nagaraj S, Dec 15 '14 at 08:47

score 8 · Accepted Answer · answered Dec 15 '14 at 08:46

8

You have to do following to get new Guid.

  Guid.NewGuid()

By default it is blank.

answered Dec 15 '14 at 08:46

dotnetstep

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Callum Linington · Answer 2 · 2014-12-15T08:54:15.053

new Guid();

This just instantiates a new structure of Guid. It doesn't generate any values for it.

From the MSDN docs:

Initializes a new instance of the Guid structure.

To get a new GUID each time with a new value:

Guid.NewGuid();

To test whether you have a new Guid or not, you can use the Guid.Empty

if (myGuid == Guid.Empty())

Aside

Here's another interesting snippet, I've been told for value types to always use == to do equality comparing, and for reference types you can do .Equals(). However, looking under the hood of the Guid implementation, it seems very safe to use .Equals():

    public bool Equals(Guid g)
    {
        // Now compare each of the elements
        if(g._a != _a)
            return false;
        if(g._b != _b)
            return false;
        if(g._c != _c)
            return false;
        if (g._d != _d)
            return false;
        if (g._e != _e)
            return false;
        if (g._f != _f)
            return false;
        if (g._g != _g)
            return false;
        if (g._h != _h)
            return false;
        if (g._i != _i)
            return false;
        if (g._j != _j)
            return false;
        if (g._k != _k)
            return false;

        return true;
    }

I don't know about anyone else, I've always been interested in whether you should do == or .Equals()

Why this code is everytime generating 0000-0000 as guid?

2 Answers2