How to pass a parameter as a reference with MethodInfo.Invoke

Question

How can I pass a parameter as a reference with MethodInfo.Invoke?

This is the method I want to call:

private static bool test(string str, out byte[] byt) 

I tried this but I failed:

byte[] rawAsm = new byte[]{}; MethodInfo _lf = asm.GetType().GetMethod("test", BindingFlags.Static |  BindingFlags.NonPublic); bool b = (bool)_lf.Invoke(null, new object[] {     "test",     rawAsm }); 

The bytes returned are null.

Answer 1

You need to create the argument array first, and keep a reference to it. The out parameter value will then be stored in the array. So you can use:

object[] arguments = new object[] { "test", null }; MethodInfo method = ...; bool b = (bool) method.Invoke(null, arguments); byte[] rawAsm = (byte[]) arguments[1]; 

Note how you don't need to provide the value for the second argument, because it's an out parameter - the value will be set by the method. If it were a ref parameter (instead of out) then the initial value would be used - but the value in the array could still be replaced by the method.

Short but complete sample:

using System; using System.Reflection;  class Test {     static void Main()     {         object[] arguments = new object[1];         MethodInfo method = typeof(Test).GetMethod("SampleMethod");         method.Invoke(null, arguments);         Console.WriteLine(arguments[0]); // Prints Hello     }      public static void SampleMethod(out string text)     {         text = "Hello";     } }