// Task 5 - the LINQ part - by first and last names in descending orders
public static Student[] OrderByNames(Student[] arr)
{
var ordered =
from student in arr
orderby student.FirstName descending, student.LastName descending
select student;
Student[] array = ordered.ToArray();
return array;
}
// 3 Task - students with first name before last
public static Student[] FirstBeforeLast(Student[] arr)
{
var firstBeforeLast =
from student in arr
where student.FirstName.CompareTo(student.LastName) == -1
select student;
Student[] array = firstBeforeLast.ToArray();
return array;
}
// 4 Task - students between 18 and 24 years old
public static Student[] AgeInterval(Student[] arr)
{
var ageInterval =
from student in arr
where ((student.Age >= 18) && (student.Age <= 24))
select student;
Student[] array = ageInterval.ToArray();
return array;
}
public Student GetStudent()
{
Student Su = new Student();
DataTable dt = new DataTable();
dt = Db.TruyVan_TraVe_DataTable("select * from nguoihoc");
Su.Ma = Int32.Parse(dt.Columns[1].ToString());
Su.Ten = dt.Columns[2].ToString();
Su.Mk = dt.Columns[2].ToString();
Su.Dt = dt.Columns[2].ToString();
Su.Sn = dt.Columns[2].ToString();
return Su;
}
static void Main()
{
// Test StringBuilder
try
{
StringBuilder str = new StringBuilder("Telerik Academy Students");
Console.WriteLine(str.Substring(2));
Console.WriteLine(str.Substring(2, 4));
Console.WriteLine();
}
catch (Exception e)
{
Console.WriteLine(e.Message);
}
// Test IEnumerable extensions
int[] arr = new int[4] { 4, -23, 11, 3 };
Console.WriteLine("The min value is {0}", arr.MaxValue<int>());
Console.WriteLine("The max value is {0}", arr.MinValue<int>());
Console.WriteLine("The sum is {0}", arr.Sum<int>());
Console.WriteLine("The product is {0}", arr.Product<int>());
Console.WriteLine("The average is {0}", arr.Average<int>());
Console.WriteLine();
// Test LINQ and Lambda functions
// 3 task test
Student[] std = new Student[5]{
new Student("Acho","Georgieva",22),
new Student("Acho","Georgiev",22),
new Student("Galen", "Asenov",16),
new Student("Anton", "Antonov", 40),
new Student("Milko","Manchev",34)
};
Student[] studentArr = LINQmethods.FirstBeforeLast(std);
Console.WriteLine("FirstBeforeLast:");
foreach (var c in studentArr)
Console.WriteLine(c);
Console.WriteLine();
// 4 task test
studentArr = LINQmethods.AgeInterval(std);
Console.WriteLine("Age Between 18 and 24:");
foreach (var c in studentArr)
Console.WriteLine(c);
Console.WriteLine();
// 5 task test - first the lambda function
var ordered = std.OrderByDescending(student => student.FirstName).ThenByDescending(student => student.LastName);
Console.WriteLine("Ordered by name descending - lambda function:");
foreach (var c in ordered)
Console.WriteLine(c);
Console.WriteLine();
// Then with LINQ
studentArr = LINQmethods.OrderByNames(std);
Console.WriteLine("Ordered by name descending - LINQ:");
foreach (var c in studentArr)
Console.WriteLine(c);
Console.WriteLine();
int[] array = new int[7] { 2, 3, 5, 7, 21, 42, 43 };
// 6 task - testing first with lambda expressions
var divNumbers = Array.FindAll(array, divNumber => ((divNumber % 3 == 0) && (divNumber % 7 == 0))); // or one check - divNumber%21
Console.WriteLine("Divisible integers - first with lambda expressions.");
foreach (int c in divNumbers)
Console.WriteLine(c);
Console.WriteLine();
Console.WriteLine("Divisible integers - now with LINQ.");
int[] intArray = LINQmethods.DivisibleNumbers(array);
foreach (var c in intArray)
Console.WriteLine(c);
Console.WriteLine();
// Task 7 - create a timer delegate that can call a function in a specified interval.
// You have to use the constructor for the class - it takes the function and the
// interval in seconds - the interval must be non-negative.
Console.WriteLine("Call a function using only a delegate:");
TimerWithDelegate del = new TimerWithDelegate(FunctionToTest, 1);
// Executing the function a specific number of times by calling the Execute Timer method with
// a parameter the number of executions
del.ExecuteTimer(5);
Console.WriteLine();
// 8 Task - using events. First we create an instance of our timer class containing the timer interval
// and the number of function executions.
Console.WriteLine("Call a function with an event:");
TimerWithEvent eventTime = new TimerWithEvent(1, 5);
// Then we create an instance of the subscriber by specifying the function to be executed and the timer to
// subscribe to.
SubscriberToTimerWithEvent sub = new SubscriberToTimerWithEvent(FunctionToTest, eventTime);
// Start execution.
eventTime.StartExecution();
eventTime.StartExecution();
}
