How to set null value to int in c#?

问题:

int value=0;

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

How can I set value to null above?

Any help will be appreciated.

回答1:

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)

回答2:

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;

回答3:

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

int? value = null;

回答4:

int does not allow null, use-

int? value = 0  

or use

Nullable<int> value

回答5:

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

回答6:

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

回答7:

Use Null.NullInteger ex: private int _ReservationID = Null.NullInteger;