How to set null value to int in c#?

In .Net, you cannot assign a null value to an int or any other struct. Instead, use a Nullable<int>, or int? for short:

int? value = 0;


if (value == 0)
{
value = null;
}

Further Reading

• Nullable Types (C# Programming Guide)

You cannot set an int to null. Use a nullable int (int?) instead:

int? value = null;

Declare you integer variable as nullable eg: int? variable=0; variable=null;

Additionally, you cannot use "null" as a value in a conditional assignment. e.g...

bool testvalue = false;
int? myint = (testvalue == true) ? 1234 : null;

FAILS with: Type of conditional expression cannot be determined because there is no implicit conversion between 'int' and '<null>'.

So, you have to cast the null as well... This works:

int? myint = (testvalue == true) ? 1234 : (int?)null;

UPDATE (Oct 2021):

As of C# 9.0 you can use "Target-Typed" conditional expresssions, and the example will now work as c# 9 can pre-determine the result type by evaluating the expression at compile-time.

int does not allow null, use-

int? value = 0

or use

Nullable<int> value

 public static int? Timesaday { get; set; } = null;

OR

 public static Nullable<int> Timesaday { get; set; }

or

 public static int? Timesaday = null;

or

 public static int? Timesaday

or just

 public static int? Timesaday { get; set; }




static void Main(string[] args)
{




Console.WriteLine(Timesaday == null);


//you also can check using
Console.WriteLine(Timesaday.HasValue);


Console.ReadKey();
}

The null keyword is a literal that represents a null reference, one that does not refer to any object. In programming, nullable types are a feature of the type system of some programming languages which allow the value to be set to the special value NULL instead of the usual possible values of the data type.

https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/null https://en.wikipedia.org/wiki/Null

int ? index = null;


public int Index
{
get
{
if (index.HasValue) // Check for value
return index.Value; //Return value if index is not "null"
else return 777; // If value is "null" return 777 or any other value
}
set { index = value; }
}