2023.01.09 오전 배열 복습

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Study07
{
    class App
    {
        //생성자
        public App()
        {
            Console.WriteLine("App 생성자.");
            //길이가 5개인 배열을 생성하고 모든 요소의 값을 -1로 초기화하세요
            //같은 타입의 연속된 데이터들을 그룹하하고 관리하기 위함 - 배열의 사용 목적
            //점수를 관리하기위해 배열을 사용했을때

            int[] scores = new int[5];
            //int[] scores = { -1, -1, -1, -1, -1 };// new int[5];
            //scores[0] = -1;
            //scores[1] = -1;
            //scores[2] = -1;
            //scores[3] = -1;
            //scores[4] = -1;

            Console.WriteLine(scores.Length);
            Console.WriteLine("Start index {0}, last index : {1}", 0, scores.Length, -1);

            for (int i = 0; i < scores.Length; i++)
                if (i < scores.Length)
                {
                    scores[i] = -1;
                    Console.WriteLine("index: {0} value : {1}", i, scores[i]);
                }


            //배열의 요소에 값을 할당
            //배열의 요소에 접근하는 방법은?
            //인덱스로 접근해야한다 : 배열인스턴스[인덱스],index : 0 ~ length -1
            //ex) scores[index]
            //배열인스턴스 요소에 acess하는 것이다
            //배열의 요소에 값을 할당

            scores[0] = 80; //scores[0] scorse 배열의 0인덱스 요소에 값을 80 할당
            scores[1] = 74;
            scores[2] = 81;
            scores[3] = 90;
            scores[4] = 43;
            //scores[5] = 55; //인덱스가 배열의 범위를 벗어남 0,~4 length - 1

            int index = 0;
            index++;
            scores[index] = 82;

            int j = 0;
            int sum = 0; //for, foreach 문 안에서 값을 저장하고 싶다면 문 밖에 변수를 사용하자
            foreach (int score in scores)
            {
                Console.WriteLine("index : {0} value {1}", j, score);
                //이럴거면 뭐하러 foreach문 사용하나? 이래서 내용물만 보여줄때 쓰는이유이다
                sum = sum + score;
                j++;
            }
            Console.WriteLine("sum : {0}", sum);
            


        }
    }
}