Union

Jamshid Sodiqov

Union operatori berilgan ikkita to’plamni qo’shib dublikatlardan holi bo’lgan yangi to’plam hosil qilish uchun ishlatiladi.

Masalan:

IList<string> strList1 = new List<string>() { "One", "Two", "three", "Four" };
IList<string> strList2 = new List<string>() { "Two", "THREE", "Four", "Five" };

var result = strList1.Union(strList2);

foreach(string str in result)
        Console.WriteLine(str);

Output:

One
Two
Three
THREE
Four 
Five

Union operatori murakkab datatypelar toʻplami uchun toʻgʻri natijani qaytarmaydi.

Bu shuni anglatadiki, biz murakkab ma'lumotlar turlari bilan ishlayotganimizda, kutilganidek natijani olish uchun IEqualityComparer interfeysini implement qilishimiz kerak.

Students class uchun IEqualityComparer interfeysini quyidagi tarzda implement qilish mumkin :

public class Student 
{
    public int StudentID { get; set; }
    public string StudentName { get; set; }
    public int Age { get; set; }
}

class StudentComparer : IEqualityComparer<Student>
{
    public bool Equals(Student x, Student y)
    {
        if (x.StudentID == y.StudentID && x.StudentName.ToLower() == y.StudentName.ToLower())
            return true;

        return false;
    }

    public int GetHashCode(Student obj)
    {
        return obj.StudentID.GetHashCode();
    }
}

Endi to'g'ri natijaga erishish uchun Union metodi usulida StudentComparer sinfidan foydalanishimiz mumkin:

IList<Student> studentList1 = new List<Student>() { 
        new Student() { StudentID = 1, StudentName = "John", Age = 18 } ,
        new Student() { StudentID = 2, StudentName = "Steve",  Age = 15 } ,
        new Student() { StudentID = 3, StudentName = "Bill",  Age = 25 } ,
        new Student() { StudentID = 5, StudentName = "Ron" , Age = 19 } 
    };

IList<Student> studentList2 = new List<Student>() { 
        new Student() { StudentID = 3, StudentName = "Bill",  Age = 25 } ,
        new Student() { StudentID = 5, StudentName = "Ron" , Age = 19 } 
    };

var resultedCol = studentList1.Union(studentList2, new StudentComparer()); 

foreach(Student std in resultedCol)
    Console.WriteLine(std.StudentName);

Output:

John
Steve
Bill
Ron

Union operatori C# va VB.Net Query sintaksisida qo'llab-quvvatlanmaydi.