Dictionary Data-Structure

Links: MSDN: Dictionary

Gitbook Definition and Examples

Unity Scripting Tutorial: Dictionary

Unity TextAdventure Tutorial - Use Dictionary Inventory

Using Arrays, Lists, ArrayLists, Dictionaries, HashTable in Unity

Dictionaries: A collection of Key,Value pairs

Dictionaries provide a data-structure for storing data that has 2 associated parts, which is very useful for data associated with games, such as inventory systems, character choice systems, weapon systems, etc.

The Key is used as a index to allow storage of a value that is associated with a unique Key. Keys must be unique, there cannot be duplicate Keys in a dictionary, so we must use care when adding new elements to a dictionary object to ensure that the item's key does not already exist in the dictionary. There are several methods that can be used to test for the presence of a specific key, these helper functions prevent runtime errors in our programs.

Unity does not show Dictionary elements in the inspector.

Include as a directive at top of script: using System.Collections.Generic;

Dictionary < TKey,TValue > Dictionary - you specify the data-type of the key: Tkey, and value: TValue.

Unity does not show Dictionary elements in the inspector.

Simple Dictionary Examples:

Code Snippets

TKey: PickupType, enum type of Pickup objects

TValue: int, count of number of items

public Dictionary<PickupType, int> inventory_v1 = new Dictionary<PickupType, int>(); //initialize

inventory_v1.Add(PickupType.Gem, 1); //add an item
int gems = inventory_v1[PickupType.Gem]; //get value associated with key

inventory_v1[PickupType.Gem] = 2; //change an item

if( inventory_v1.ContainsKey( PickupType.Cow ){
  int count = inventory_v1[PickupType.Cow]
  inventory_v1[PickupType.Cow] = count +1;
}else{
   Debug.Log("No Cows")
   inventory_v1.Add( PickupType.Cow, 1); //added
}

//TryGetValue
int count = 0;
if( inventory_v1.TryGetValue( PickupType.Gem,out count){
  inventory_v1[PickupType.Gem] = count + 1;
  } 
  else{
    inventory_v1.Add(PickupType.Gem ,1);
  }