/// <summary>
/// This method invokes a method having a regular expression that validates the format of the entered employee salary.
/// </summary>
/// <param name="sender">The control that fired the event</param>
/// <param name="e">The arguments associated with the fired event.</param>
private void salary_Validating(object sender, CancelEventArgs e)
{
string textInput = salary.Text.TrimStart().TrimEnd();
if (string.IsNullOrEmpty(textInput))
{
MessageBox.Show("No salary has been entered", "Salary Slip Application", MessageBoxButtons.OK, MessageBoxIcon.Error);
salary.Focus();
}
else if (!(RegularExpressionValidator.IsValidSalary(textInput)))
{
MessageBox.Show("The entered salary is not in proper format", "Salary Slip Application", MessageBoxButtons.OK, MessageBoxIcon.Error);
salary.Focus();
}
}