传递null为空？

Question

I have the following method:

    //returns -1 on failure
    public static int Add(
        string name, string email, string password, short defaultNumWeek)
    {
        KezberPMDBDataContext db = new KezberPMDBDataContext();
        Employee employee = new Employee 
        { 
            EmployeName = name,
            EmployeEmail = email,
            EmployePassword = password,
            DefaultNumWeek = defaultNumWeek
        };
        db.Employees.InsertOnSubmit(employee);
        try
        {
            db.SubmitChanges();
        }
        catch (Exception)
        {
            return -1;
        }

        return employee.EmployeID;
    }

The last parameter is optional and can be null in the database. How can I do this without creating 2 separate methods? I have other ones that are less simple. How can I pass a base type as null?

Answer 1

Use Nullable type as

public static int Add(
        string name, string email, string password, short? defaultNumWeek)

DefaultNumWeek property of Employee mast be Nullable too.

Answer 2

static void Bar(Nullable<short> s)
{

}

or

static void Bar(short? s)
{

}

The former is merely a short hand, see Using Nullable Types

Answer 3

Change the definition to:

public static int Add(
        string name, string email, string password, short? defaultNumWeek = null)

This allows you to call the same function while omitting the defaultNumWeek parameter.

Answer 4

只要传递它，如果它为空则不要使用它。

Answer 5

You can handle this with Nullable Types . C# has an alias where you attach a question mark (?) to a struct type (like short).

This allows you to compare it against null, ask whether it has a value and so forth.