Error checking for if a person enters an incorrect name

Question

How would I check for errors. If a person enters an incorrect name or doesnt spell it correctly I would like for a messagebox.show to display a message stating "Incorrect name or spelling"

private void button1_Click(object sender, EventArgs e)
    {
        String Andrea;
        String Brittany;
        String Eric;
        if (textBox1.Text == ("Andrea"))
            Commission.Text = (Convert.ToDouble(textBox2.Text) / 10).ToString();
        if (textBox1.Text == ("Brittany"))
            Commission.Text = (Convert.ToDouble(textBox2.Text) / 10).ToString();
        if (textBox1.Text ==("Eric"))
            Commission.Text = (Convert.ToDouble(textBox2.Text) / 10).ToString();

        {

        } 

    }

Answer 1

You will need to keep a list or 'dictionary' of correct names.

Then, you can match the text against the entries in the dictionary.

Code would look similar to the following:

HashSet<string> correctNames = ;// initialize the set with the names you want

private void button1_Click(object sender, EventArgs e)
{
    if (correctNames.Contains(textBox1.Text))
        Commission.Text = (Convert.ToDouble(textBox2.Text) / 10).ToString();
    else 
    {
       MessageBox.Show("The speling of the naem " + textBox1.Text + " was incorect", "Bad Spelling Error");
    }
}

_{You probably want to use correct spelling in your implementation.}

Have a look at the documentation for HashSet to get a better idea of how to use it.