Question

I create a user control group sub-class. There are two radiobuttons. I need to create event handlers for them. I have two directions to go. One is to create event handlers in the sub class and let the event handler to change a constant in the subclass. I will use a function to check the sub class constant in the upper class. The other one is to create event handlers in the upper class for the sub-class radio buttons. The following is my code for method 1.Note I have commented out two lines (they are the event handler creation) because they are wrong because they create errors please help

    using namespace System;
using namespace System::ComponentModel;
using namespace System::Collections;
using namespace System::Windows::Forms;
using namespace System::Data;
using namespace System::Drawing;
using namespace System::Collections;
using namespace System::Collections::Generic;

#include <stdio.h>
#include <stdlib.h>
#using <mscorlib.dll>

            public ref class temp_groupbox: public GroupBox
            {
            public: temp_groupbox(int a, int b, String ^groupboxname){

                          // Create and initialize a GroupBox and two RadioButton controls.
                            //GroupBox^ groupBox1 = gcnew GroupBox;
                            RadioButton^ radioButton1 = gcnew RadioButton;
                            RadioButton^ radioButton2 = gcnew RadioButton;

                          // Add the RadioButtons to the GroupBox.
                            this->Controls->Add( radioButton1 );
                            this->Controls->Add( radioButton2 );

                            this->Location = System::Drawing::Point(a, b);
                            this->Size = System::Drawing::Size(500, 100);
                            this->TabIndex = 0;
                            this->TabStop = false;

                            radioButton1->Name = L"radioButton1";
                            radioButton2->Name = L"radioButton2";


                            radioButton1->Size = System::Drawing::Size(85, 17);
                            radioButton2->Size = System::Drawing::Size(85, 17);

                            radioButton1->Location = System::Drawing::Point(30, 40);
                            radioButton2->Location = System::Drawing::Point(30, 90);

                            radioButton1->TabIndex = 0;
                            radioButton1->TabStop = true;

                            radioButton2->TabIndex = 1;
                            radioButton2->TabStop = true;

                            radioButton1->UseVisualStyleBackColor = true;
                            radioButton1->CheckedChanged += gcnew System::EventHandler(this, radioButton1_CheckedChanged);
                            radioButton2->UseVisualStyleBackColor = true;
                            radioButton2->CheckedChanged += gcnew System::EventHandler(this, radioButton2_CheckedChanged);

                            this->SuspendLayout();
                            this->ResumeLayout(false);
                            this->PerformLayout();
                }


            public: RadioButton^ radioButton1;
            public: RadioButton^ radioButton2;
            public: int anss;

            void radioButton1_CheckedChanged(Object^ sender, EventArgs^ e)
            {
                anss = 1;
            }

            void radioButton2_CheckedChanged(Object^ sender, EventArgs^ e)
            {
                anss = 2;
            }

            };// end ref class

Answer 1

Do you have methods radioButton1_CheckedChanged and radioButton2_CheckedChanged defined?

void radioButton1_CheckedChanged(Object^ sender, EventArgs^ e)
{
}

void radioButton2_CheckedChanged(Object^ sender, EventArgs^ e)
{
}

If these methods already exist, please list the error message you’re getting. It’s hard to figure out how to fix something if we don’t know what’s wrong.

---

You need to specify the full class name of the method you’re creating a delegate for, and use the & to take the address of it.

gcnew System::EventHandler(this, &temp_groupbox::radioButton1_CheckedChanged)