C#

<br />
[Platform(Platform.Win32NT)]<br />
[DllImport("somedll.dll")]<br />
public static extern int APIcall([In] int param1, float param2);<br />
<br />
<br />
public int CallTheAPI(int param1, float param2)<br />
{<br />
if (!System.Environment.OSVersion.Platform.ToString().Equals("Win32NT"))<br />
{<br />
throw new ApplicationException("Your current platform is not a Win32NT operating system.");<br />
}<br />
return APICall(parma1, param2); //If the current platform is not Win32NT it should <br />
}<br />
<br />
<br />

enum Platform
{
    XP,
    NT,
    Vista
}

class PlatformNameAttribute : Attribute
{
    public PlatformNameAttribute(Platform platForm)
    {
        this.Platform = platForm;
    }

    public Platform Platform { get; set; }
}

class Program
{
    [PlatformName(Platform.NT)]
    static void SomeAPICall()
    {
        Console.WriteLine("NT");
    }

    [PlatformName(Platform.XP)]
    static void SomeOtherAPICall(int x)
    {
        Console.WriteLine("XP");
    }

    static Platform GetCurrentPlatform() { return Platform.NT; }

    static void ExecuteAPICall(Delegate d, params object[] parameters)
    {
        var attributes = d.Method.GetCustomAttributes(typeof(PlatformNameAttribute), false);

        if (attributes != null && attributes.Count() > 0)
        {
            var platformAttribute = (PlatformNameAttribute)attributes[0];

            if (platformAttribute.Platform != GetCurrentPlatform())
            {
                throw new InvalidOperationException("Platform Type mismatch");
            }

            d.DynamicInvoke(parameters);
        }
    }

    static void Main(string[] args)
    {
        ExecuteAPICall(new Action(SomeAPICall));
        ExecuteAPICall(new Action<int>(SomeOtherAPICall), 2);
    }

public class Class1
	{
		public enum Protocol
		{
			Digital,
			Analog
		}
		public enum Model
		{
			Digital1,
			Digital2,
			Analog1,
			Analog2
		}

		public static Protocol m_selectedProtocol;
		public static Model m_ModelSelected;

		public static Protocol SelectedProtocol
		{
			get { return Class1.m_selectedProtocol; }
			set { Class1.m_selectedProtocol = value; }
		}
		public static Model ModelSelected
		{
			get { return Class1.m_ModelSelected ; }
			set { Class1.m_ModelSelected= value; }
		}

	}

private void button1_Click(object sender, EventArgs e)
{
    Class1.SelectedProtocol = Class1.Protocol.Analog;
}

if (rdAnalog.Checked == true)
 {
    Class1.SelectedProtocol = Protocol.Analog;


    if (Analog1.Checked == true)
    {
        Class1.ModelSelected = Model.Analog1;
    }
    else if (Analog2.Checked == true)
    {
        Class1.ModelSelected = Model.Analog2;
    }
    else
    {
        return;
    }
 }  /*This Curly bracket you have missed */
 else
 {
    return;
 }