Question

I am creating an expense tracking report using Visual Studio 2010 C# where the user can see the total of all the expenses while he/she is still typing the values for each expenses so that he/she could know if the total is equivalent or higher than her budget. My question is, how can I get the total of all the expenses the user is entering without having him/her press any button to calculate? Please help. Thanks

This is the screenshot of the form:

This is the code:

private void textBox3_TextChanged(object sender, EventArgs e)
    {
        tot = 0;
        tot += int.Parse(textBox1.Text); // No error checking, just an example
        tot += double.Parse(textBox2.Text);
        textBox3.Text = tot.ToString();
    }

Answer 1

You should catch TextChange event on every textbox (it could be one for all)

double tot = 0;
private void tb_TextChanged(object sender, EventArgs e)
{
    // Update sum here
    tot = 0;
    tot += Int.Parse(Textbox1.Text); // No error checking, just an example
    tot += Double.Parse(Textbox2.Text); // Be careful to decimal separator

    TotalTextBox.Text = tot.ToString();
}