Dotnet compiler giving Dereference of a possibly null reference only for first array of nullable array

Question

I am running an asp.net core application , I have a class with a string array member which i have declared as nullable. When i am using the array elements in my other classes, the compiler gives me Dereference of a possibly null reference warning only for the first member of the array and not for the others.

PS sorry for bad formatting of the code. There are no syntax errors

I am getting a warning for possible null values for DummyData[0] but not for DummyData[1] and others.

public class Dummy
{
    public string[]? DummyData { get; set; }
}

This is where i am using DummyData

result += DummyDataConstants.SOM + DummyDataConstants.cmdMainArray[(int)DummyDataConstants.CMD_MAIN_ID_e.CMD_MAIN_REQ_LOG]
                                    + DummyDataConstants.FSP + DummyDataConstants.SMART_CODE + DummyDataConstants.FSP + commandParams.DummyData[0]  // warning given for commandParams.DummyData[0] 

+ DummyDataConstants.FSP + commandParams.DummyData[1]  // no warning here
+ DummyDataConstants.FSP + commandParams.MediaClientType + DummyDataConstants.FSP + commandParams.DummyData[2] + DummyDataConstants.FSP + newGuid.ToString() + DummyDataConstants.FSP + DummyDataConstants.EOM

Answer 1

Compiler will emit warning only when your code may dereference null. In this case only place where this is considered to be possible is commandParams.DummyData[0] since if it is (i.e. commandParams.DummyData == null) you will encounter NullReferenceException here, hence all other attempts either will not happen or will work with definitely not null reference. If you will use null-conditional element access operator for the first element you will see the warning "transferred" to the next one:

void WarningTest(int[]? array)
{
     Console.WriteLine(array?[0]);   
     Console.WriteLine(array[0]); // warning 
     Console.WriteLine(array[0]); // no warning 
}

Demo @sharplab.io