c# - What is a method that's inside another method called?

Question

What type of method is String dgvValue(int cell) in the below code?

private void btnEdit_Click(object sender, EventArgs e)
{
    if (dgvGuestList.SelectedRows.Count > 0)
    {
        String dgvValue(int cell)
        {
            return dgvGuestList.SelectedRows[0].Cells[cell].Value.ToString();
        }
        
        editGuest editGuest = new editGuest(int.Parse(dgvValue(0)), dgvValue(1), 
        int.Parse(dgvValue(2)), dgvValue(0), dgvValue(0), dgvValue(0), dgvValue(0));
        editGuest.ShowDialog();
    }
    else
    {
        DialogResult error = MessageBox.Show("No row selected.", "Error", MessageBoxButtons.OK, 
        MessageBoxIcon.Exclamation);
    }
}

question from:https://stackoverflow.com/questions/62619932/what-is-a-method-thats-inside-another-method-called

Answer 1

It's a feature of c# called local functions, introduced in c# 7:

Many designs for classes include methods that are called from only one location. These additional private methods keep each method small and focused.
Local functions enable you to declare methods inside the context of another method. Local functions make it easier for readers of the class to see that the local method is only called from the context in which it is declared.