某种int的C＃方法参数是否可以接受null并可以更新参数

Question

As below code expressed, I want SomeMethod

• Have a parameter of some kind of int
• can accept null as parameter

• if parameter is none null, it will use it's value, then update the value of argument variable in Caller2

   void Caller1() { SomeMethod(null, ...); } void Caller2() { int argument = 123; SomeMethod(argument, ...); Debug.Assert(argument == 456); } void SomeMethod(SomeKindOfInt parameter, ...) { if (parameter != null) { // use the value of parameter; parameter = 456; // update the value of argument which is in Caller2 } } 

Tried and declare:

• ref int can't accept null
• int? can't update argument in caller
• Create a custom Wrapper class of int did this, but is there a light way or does C# or .net have some build in tech?
• It's not good to split it into two methods because there's a big logic inside which is common whenever parameter is null or none null.

Answer 1

Almost there, you can use int? to allow null value and put the ref keyword.

static void Main(string[] args)
{
    int? test1 = null;
    SomeMethod(ref test1);
    Console.WriteLine(test1);
    // Display 456

    int? test2 = 123;
    SomeMethod(ref test2);
    Console.WriteLine(test2);
    // Display 123

    Console.ReadLine();
}

static void SomeMethod(ref int? parameter)
{
    if (parameter == null)
    {
        parameter = 456;
    }
}