How to get a value from a child form back to a caller form

Introduction

This simple article explains how you can get a value on a different form on to a caller form.

Background

Basically you may keep a method to access the values in the child form window. Using a GET method is better than exposing the entire object to outside.

Using the code

Firstly, you need to have a method in the child form to get the values. 

public DataGridViewSelectedRowCollection getselectedrow()
{
    return dataGridView1.SelectedRows;
}

Some example code to show how the child form is instantiated and the method being called:

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }
    Form2 form2show;
    private void button1_Click(object sender, EventArgs e)
    {
        if ((form2show==null) || (form2show.IsDisposed==true))
        {
            form2show = new Form2();
        }
        form2show.Show();
    }
    private void button2_Click(object sender, EventArgs e)
    {
        if ((form2show==null) || (!form2show.Visible))
        {
            return;
        }
        DataGridViewSelectedRowCollection dsr = form2show.getselectedrow();
        if ((dsr == null) || (dsr.Count == 0))
        {
            return;
        }

        textBox1.Text = dsr[0].Cells[1].Value.ToString();
    }
}

Points of Interest

It's always better to use a method to access properties like above. We call them GET methods. It's recommended than exposing an entire object to outside.