C# Online Test

Refactor the AlertService and AlertDAO classes:

• Create a new interface, named IAlertDAO, that contains the same methods as AlertDAO.
• AlertDAO should implement the IAlertDAO interface.
• AlertService should have a constructor that accepts IAlertDAO.
• The RaiseAlert and GetAlertTime methods should use the object passed through the constructor.

Implement the UniqueNames method. When passed two arrays of names, it will return an array containing the names that appear in either or both arrays. The returned array should have no duplicates.

For example, calling MergeNames.UniqueNames(new string[]{'Ava', 'Emma', 'Olivia'}, new string[]{'Olivia', 'Sophia', 'Emma'}) should return an array containing Ava, Emma, Olivia, and Sophia in any order.

User interface contains two types of user input controls: TextInput, which accepts all characters and NumericInput, which accepts only digits.

Implement the class TextInput that contains:

• Public method void Add(char c) - adds the given character to the current value
• Public method string GetValue() - returns the current value

Implement the class NumericInput that:

• Inherits TextInput
• Overrides the Add method so that each non-numeric character is ignored

For example, the following code should output "10":

TextInput input = new NumericInput();
input.Add('1');
input.Add('a');
input.Add('0');
Console.WriteLine(input.GetValue());