How to: Specify an out Parameter
This sample shows how to specify that a function parameter is an out parameter and how to call that function from a C# program.
An out parameter is specified in Visual C++ with OutAttribute .
Example
The first part of this sample is a Visual C++ DLL with a type that contains a function with an out parameter.
// cpp_out_param.cpp
// compile with: /LD /clr:safe
using namespace System;
public value struct TestStruct {
static void Test([Runtime::InteropServices::Out] String^ %s) {
s = "a string";
}
};
This is a C# client that consumes the Visual C++ component created in the previous example.
// cpp_out_param_2.cs
// compile with: /reference:cpp_out_param.dll
using System;
class TestClass {
public static void Main() {
String t;
TestStruct.Test(out t);
System.Console.WriteLine(t);
}
}
a string