HashTable

Tolibjonov Abdulloh

Bu mavzuni boshlashdan oldin Hash kod va Hash jadval haqida bilib olsak !

Hash kod – Ma'lumotlar to'plamida qidiruv va kiritishga yordam beruvchi, hash jadvalga asoslangan raqamli qiymat.

Hash jadval – bu kalit/qiymat elementlarni saqlash uchun maxsus to'plam. Stack, Array, List va Queue ni o'rniga Hash jadval 2 xil qiymat saqlaydi (kalit va qiymat).

Hashtable – Hash kodga asoslangan, kalit/qiymat ko'rinishidagi juft elementlar to'plami. Boshqacha qilib aytganda, Hashtable ma'lumotlarni saqlash uchun hash jadvaldan foydalanadi (hash table). Hashtable (non-generic) generic bo'lmagan to'plamdir, shu sababdan kodni yuqorisiga System.Collections ni yozish kifoya.

MUHIM QOIDALAR!

• Hashtable kaliti null qiymatli bo'lishi mumkin emas

• Hashtable elementlari kalit/qiymat juftligida bo'ladi

• Kalitni nomi boshqa kalitlar bilan bir xil bo'lmasligi kerak

Hashtable ni qanday yaratamiz ?

1-Bosqich. Kod yuqorisiga using System.Collections; kiritamiz

    using System.Collections.Generic;

2-Bosqich. Ko'rsatilgan tartibda Hashtable ni yaratamiz

    Hashtable hashtable_nomi = new Hashtable();

hashtable_nomi – bu Hashtable nomi ixtiyoriy nom yozishingiz mumkin

3-Bosqich. Element qo'shamiz, har doimgidek 2 xil usulda :) 1) Hashtable ni yaratiboq element qo'shing (xuddi massivdek)

    Hashtable hashtable_nomi = new Hashtable() {{1, "element1"}, {2, "element2"}};

2) Add() funksiyasi yordamida element qo'shing

     Hashtable hashtable_nomi = new Hashtable();
        hashtable_nomi.Add(1, "element1");
        hashtable_nomi.Add(2, "element2");
        hashtable_nomi.Add(3, "element3");

Misol:

  using System;
  using System.Collections;
  public class Program
  {
      public static void Main()
      {
         Hashtable hashtable_nomi = new Hashtable();
         hashtable_nomi.Add(1, "element1");
         hashtable_nomi.Add(2, "element2");
          hashtable_nomi.Add(3, "element3");
          foreach (DictionaryEntry t in hashtable_nomi)
          {
              Console.WriteLine($"kalit: {t.Key} qiymat: {t.Value}");
          }
      }
  }

DictionaryEntry haqida SortedList mavzusidagi misollar davomida ma'lumot berib o'tilgan.

Hashtable da elementlarni qanday o'chiramiz ?

Remove() va Clear() funksiyalari orqali

Remove() – funksiyasidan foydalanib kalitni kiritish orqali elementlarni o'cherish mumkin

Clear() – funksiyasi Hashtable dagi barcha elementlarni o'cherish uchun

Misol:

  using System;
  using System.Collections;
  public class Program
  {
      public static void Main()
      {
         Hashtable hashtable_nomi = new Hashtable();
         hashtable_nomi.Add(1, "element1");
         hashtable_nomi.Add(2, "element2");
         hashtable_nomi.Add(3, "element3");
         hashtable_nomi.Remove(2);
         foreach (DictionaryEntry t in hashtable_nomi)
          {
              Console.WriteLine($"kalit: {t.Key} qiymat: {t.Value}");
         }
          Console.WriteLine("*********************************");
          hashtable_nomi.Clear();
          foreach (DictionaryEntry t in hashtable_nomi)
          {
              Console.WriteLine($"kalit: {t.Key} qiymat: {t.Value}");
          }
      }
  }

Hashtable elementlarni bor yoki yo'qligini qanday bilamiz?

Contains() – funksiyasi Hashtableda bizga kerakli kalit bor yoki yo'qligini tekshriadi

ContainsKey() – Contains() bilan bir xil

ContainsValue() – funksiyasi Hashtableda bizga kerakli qiymat bor yoki yo'qligini tekshiradi

Misol:

  using System;
  using System.Collections;
  public class Program
  {
      public static void Main()
      {
          Hashtable hashtable_nomi = new Hashtable();
          hashtable_nomi.Add(1, "element1");
          hashtable_nomi.Add(2, "element2");
          hashtable_nomi.Add(3, "element3");
          Console.WriteLine(hashtable_nomi.Contains(1));
          Console.WriteLine(hashtable_nomi.ContainsKey(6));
          Console.WriteLine(hashtable_nomi.ContainsValue("element3"));
      }
  }

True bo'lganini sababi Hashtable kaliti 1 ga teng bo'lgan elementi bor

False bo'lganini sababi kaliti 6ga teng bo'lgan elementi yo'q

True bo'lganini sababi Hashtable ni qiymati "element3" ga teng bo'lgan elementi bor