# HashTable

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.

{% hint style="info" %}
**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
{% endhint %}

## Hashtable ni qanday yaratamiz ?

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

```csharp
    using System.Collections.Generic;
```

**2-Bosqich.** Ko'rsatilgan tartibda **Hashtable** ni yaratamiz

```csharp
    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)

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

2\) Add() funksiyasi yordamida element qo'shing

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

## Misol:

```csharp
  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}");
          }
      }
  }
```

![](https://2189654329-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-ML4YbrwilsjU6IyB7jd%2Fsync%2Fd06f0b05317f189f7ccd752e64f14efb52616123.png?generation=1625596366879411\&alt=media)

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:

```csharp
  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}");
          }
      }
  }
```

![](https://2189654329-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-ML4YbrwilsjU6IyB7jd%2Fsync%2F50fa8f183dfdea48b28a63644d08c341a3eed724.png?generation=1625596367275028\&alt=media)

## 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:

```csharp
  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"));
      }
  }
```

![](https://2189654329-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-ML4YbrwilsjU6IyB7jd%2Fsync%2F81c451016d10d53623fcaddf37c390ecb24711e2.png?generation=1625596367060514\&alt=media)

**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