C#•16mo ago

❔ What's the reason for the warning?

I don't understand why this warning create, because I created check with if

10 Replies

you can add ! after [0] to silence the warning well i think is not null instead of != would silence the warning

Angius•16mo ago

if (products[0] is {} p)
{
    val = p.Name;
}

if (products[0] is {} p)
{
    val = p.Name;
}

corteZz-1OP•16mo ago

okey. thanks

Jimmacle•16mo ago

why do you have Product?[] instead of Product[]? does that method return a collection that might have null elements? that's why the warning is there in the first place, you're telling the compiler that you expect some elements might be null

corteZz-1OP•16mo ago

Well, the ?. operator indicates that the type can accept null. Because of this, the compiler will generate warnings everywhere to prompt null checks. I actually implemented the null check, but the warning didn't go away.

Jimmacle•16mo ago

right, so the root question is does GetProducts give you a collection that can have null elements? why would it do that?

Unknown User•16mo ago

Message Not Public

corteZz-1OP•16mo ago

I know, my question, okey I will show you two code, what is difference? why does one of them have a "warning" and the other one doesn't? 1) first one:

 namespace LanguageFeatures.Controllers
{
    public class HomeController : Controller
    {
        public ViewResult Index()
        {
            Product?[] products = Product.GetProducts();
            Product? p = products[0];
            string val;
            if (p != null)
            {
                val = p.Name;
            }
            else
            {
                val = "No value";
            }
            return View(new string[] { val });
        }
    }
}

 namespace LanguageFeatures.Controllers
{
    public class HomeController : Controller
    {
        public ViewResult Index()
        {
            Product?[] products = Product.GetProducts();
            Product? p = products[0];
            string val;
            if (p != null)
            {
                val = p.Name;
            }
            else
            {
                val = "No value";
            }
            return View(new string[] { val });
        }
    }
}

2) another one:

namespace LanguageFeatures.Controllers
{
    public class HomeController : Controller
    {
        public ViewResult Index()
        {
            Product?[] products = Product.GetProducts();
           
            string val;
            if (products[0] != null)
            {
                val = products[0].Name;
            }
            else
            {
                val = "No value";
            }
            return View(new string[] { val });
        }
    }
}

namespace LanguageFeatures.Controllers
{
    public class HomeController : Controller
    {
        public ViewResult Index()
        {
            Product?[] products = Product.GetProducts();
           
            string val;
            if (products[0] != null)
            {
                val = products[0].Name;
            }
            else
            {
                val = "No value";
            }
            return View(new string[] { val });
        }
    }
}

Second has warning

Unknown User•16mo ago

Message Not Public

Accord•16mo ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ What's the reason for the warning?