(재연습) 컬렉션<>

List<T>

using System;
using System.Collections;
using System.Collections.Generic;

namespace Study0124
{
    class Program
    {
        static void Main(string[] args)
        {
            List<int> list = new List<int>();
            list.Add(100);
            list.Add(200);
            Console.WriteLine(list.Count); //2   //list안의 갯수
            for(int i=0; i<list.Count; i++)
            {
                int num = list[i];
                Console.WriteLine(num);     //100/200
            }

            list[1] = 300;
            bool isContains = list.Contains(100);
            Console.WriteLine(isContains);  //True
        }
    }
}

연습

using System;
using System.Collections;
using System.Collections.Generic;

namespace Study0124
{
    class Program
    {
        static void Main(string[] args)
        {
            List<int> list = new List<int>();
            for (int i = 0; i < 5; i++)
                list.Add(i);

            foreach (int element in list)
                Console.Write($"{element} ");
            Console.WriteLine();    //0 1 2 3 4

            list.RemoveAt(2);

            foreach (int element in list)
                Console.Write($"{element} ");
            Console.WriteLine();    //0 1 3 4

            list.Insert(2, 2);

            foreach (int element in list)
                Console.Write($"{element} ");
            Console.WriteLine();    //0 1 2 3 4

        }
    }
}

Queue<T> 연습

using System;
using System.Collections;
using System.Collections.Generic;

namespace Study0124
{
    class Program
    {
        static void Main(string[] args)
        {
            Queue<int> q = new Queue<int>();

            q.Enqueue(1);
            q.Enqueue(2);
            q.Enqueue(3);

            bool contains = q.Contains(3);
            Console.WriteLine(contains);    //True

            int peek = q.Peek();
            Console.WriteLine(peek);    //1

            int num = q.Dequeue();
            Console.WriteLine(num);     //1

            Console.WriteLine(q.Count);     //2

            foreach (int element in q)
                Console.WriteLine(element);   //2/3

            Console.WriteLine(q.Count);     //2
        }
    }
}

Dictionary<TKey, TValue>

using System;
using System.Collections;
using System.Collections.Generic;

namespace Study0124
{
    class Program
    {
        static void Main(string[] args)
        {
            Dictionary<int, string> dic = new Dictionary<int, string>();

            dic.Add(100, "홍길동");
            //dic.Add(100, "임꺽정"); (키가 중복 되서는 안됨)
            dic.Add(101, "홍길동");    
            dic.Add(102, null);     //가능 string 참조형식 
            dic[103] = "장길산";   //가능 [키 값] = 값 

            //Contains 
            bool b0 = dic.ContainsKey(103);
            bool b1 = dic.ContainsValue("장길산");

            //단일 요소값 가져오기 
            string name = dic[103];
            Console.WriteLine(name);    //장길산

            dic.Remove(103);    //키로 지움 

            Console.WriteLine(dic.Count);   //3

            foreach (KeyValuePair<int, string> pair in dic)
            {
                Console.WriteLine("key: {0}, val: {1}", pair.Key, pair.Value);
            }
            
        }
    }
}