You are creating aWindows Forms application for a courier company by using the .NET
Framework 3.5.You create a form that allows customers to track the progress of their
shipments. The form contains the following elements:
A text box named txtTN that allows users to enter a tracking number
An ErrorProvider control named ErrorProvider1 that informs users of an invalid
tracking number
A function named ValidTrackingNumber that validates tracking numbers
You need to ensure that the txtTN text box is validated. Which code segment should you use?
A.
private void txtTN_Validating(object sender, CancelEventArgs e)
{
if (!ValidTrackingNumber(txtTN.Text))
{
errorProvider1.SetError(txtTN, “Invalid Tracking
Number”);
Cancel = true;
}
else
errorProvider1.SetError(txtTN, “”);
}
B.
private void txtTN_Validating(object sender, CancelEventArgs e)
{
if (!ValidTrackingNumber(txtTN.Text))
errorProvider1.SetError(txtTN, “Invalid Tracking
Number”);
else
{
errorProvider1.SetError(txtTN, “”);
Cancel = true;
}
}
C.
private void txtTN_Validated(object sender, EventArgs e)
{
if (!ValidTrackingNumber(txtTN.Text)) errorProvider1.SetError(txtTN, “Invalid Tracking
Number”);
else
{
errorProvider1.SetError(txtTN, “”);
txtTN.Focus();
}
}
D.
private void txtTN_Validated(object sender, EventArgs e)
{
if (!ValidTrackingNumber(txtTN.Text))
{
errorProvider1.SetError(txtTN, “Invalid Tracking
Number”);
txtTN.Focus();
}
else
errorProvider1.SetError(txtTN, “”);
}
Explanation:
protected void textBox1_Validating (object sender, System.ComponentModel.
CancelEventArgs e)
{
try
{
// Check to see if the TextBox contains a numeric value by trying
// to parse the string
double x = double.Parse(textBox1.Text);
errorProvider1.SetError(textBox1, “”);
}
catch (System.FormatException ex)
{
// If the text box does not contain a numeric value,
// set the error on the TextBox
errorProvider1.SetError(textBox1, “The value must be numeric”);
}
}MCTS Self-Paced Training Kit (Exam 70-505): Microsoft.Net Framework 3.5-Windows Forms Application Development (pg. 581)