How Can I Access Methods Within a Dynamically Loaded DLL in a C# Console Application?

Dynamic loading of DLL in C#

C# allows DLLs to be loaded and used dynamically at runtime. The Assembly.LoadFile() method allows loading a DLL into an application.

Problem: Unable to use methods from a loaded DLL in a console application

Users reported being able to load the DLL but not being able to access its methods. This is because the C# compiler cannot pre-resolve types and members in the DLL. To call methods in a DLL, you need to use reflection or dynamic objects.

Solution 1: Use Reflection

Reflection allows obtaining type metadata and calling its members at runtime. Using reflection requires explicitly calling the method:

<code class="language-csharp">// 加载 DLL
var assembly = Assembly.LoadFile(@"C:\visual studio 2012\Projects\ConsoleApplication1\ConsoleApplication1\DLL.dll");

// 遍历 DLL 中导出的类型
foreach (Type type in assembly.GetExportedTypes())
{
    // 创建类型实例
    var instance = Activator.CreateInstance(type);

    // 调用方法 (假设方法名为 "Output" 并接受一个字符串参数)
    type.InvokeMember("Output", BindingFlags.InvokeMethod, null, instance, new object[] { "Hello" });
}</code>

Solution 2: Use dynamic objects (.NET 4.0 and above)

Dynamic objects allow calling DLL methods in code without explicit type conversion and with a simpler syntax:

<code class="language-csharp">// 加载 DLL
var assembly = Assembly.LoadFile(@"C:\visual studio 2012\Projects\ConsoleApplication1\ConsoleApplication1\DLL.dll");

// 遍历 DLL 中导出的类型
foreach (Type type in assembly.GetExportedTypes())
{
    // 创建动态实例
    dynamic instance = Activator.CreateInstance(type);

    // 调用方法 (假设方法名为 "Output" 并接受一个字符串参数)
    instance.Output("Hello");
}</code>

Both solutions show how to dynamically access methods in a DLL. Which method you choose depends on your .NET version and personal preference. Reflection provides finer control, while dynamic objects simplify code. Note that @"C:visual studio 2012ProjectsConsoleApplication1ConsoleApplication1DLL.dll" needs to be replaced with the actual path to your DLL.

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