c＃中给出警告的结构字段永远不会分配给，并且始终具有默认值0

Question

I have very simple struct as below:

 public struct ShFileInfo
 {
     public int hIcon;
     public int iIcon;
     public int dwAttributes;
 }

I have enabled warning as error . Now for all three int getting error

Field is never assigned to,and will always have its default value 0

Obviously I will get error if I try to initialize the int to 0 . Is there any way to handle this without disabling warning as error.

Answer 1

I had been receiving the warning when I copy pasted author's code.

You can define a constructor for the Struct like this

public struct ShFileInfo
    {
        public int hIcon;
        public int iIcon;
        public int dwAttributes;

        public ShFileInfo(int x,int y, int z)
        {
            hIcon = x;
            iIcon = y;
            dwAttributes = z;
        }
    }

You can also use a constructor with just one parameter and initialize all

  public ShFileInfo(int x)
        {
            hIcon = x;
            iIcon = 0;
            dwAttributes = 0;
        }

Answer 2

If your struct is inside internal class then you get this warrning

internal class WrapperClass
{
    public struct ShFileInfo
    {
        public int hIcon;
        public int iIcon;
        public int dwAttributes;
    }
}   

when you change internal access to public then warnings gone:

public class WrapperClass
{
    public struct ShFileInfo
    {
        public int hIcon;
        public int iIcon;
        public int dwAttributes;
    }
}

Answer 3

Since you are using this structure for P/Invoke only, I'd simply disable the warning locally:

#pragma warning disable 0649
public struct ShFileInfo
{
    public int hIcon;
    public int iIcon;
    public int dwAttributes;
}
#pragma warning restore 0649

The compiler has no way of knowing that your structure is assigned in the unmanaged code, but since you know, there's little hurt in simply disabling the warning.