보시면 아시겠지만, 반복 때문에 길이만 길었지 완전 기초중의 기초입니다.

//성적표 ver1.1

#include <iostream>
using namespace std;

int main()
{
        while (1)
        {
                cout << "\n------메뉴------\n";
                cout << "1. 학생 성적 추가\n";
                cout << "2. 전체 성적 보기\n";
                cout << "Q. 프로그램 s종료 \n";
                cout << "-----------------\n";
                cout << "원하는 작업의 번호를 입력하세요." ;
                
                
                int S1_No, S2_No, S3_No;
                int S1_Kor, S2_Kor, S3_Kor;
                int S1_Eng, S2_Eng, S3_Eng;
                int S1_Math, S2_Math, S3_Math;
                float S1_Ave, S2_Ave, S3_Ave;
                float TotalAve = 0.0f;
                int NumberOfStudent = 0;
                
                
                char select;
                cin >> select;
                
                switch (select)
                {
                case '1':
                        {
                                if (3==NumberOfStudent)
                                {                                
                                        cout<< "\n더 이상 입력할 수 없습니다.\n";
                                        break;
                                }
                                
                                int Kor, Eng, Math;
                                
                                cout << "국어, 영어, 수학 점수를 입력하세요. : ";
                                cin >> Kor >> Eng >> Math;
                                
                                float Ave = float(Kor+Eng+Math)/3.0f;
                                
                                if (0==NumberOfStudent)
                                {
                                        S1_No = NumberOfStudent + 1;
                                        S1_Kor=Kor;
                                        S1_Eng=Eng;
                                        S1_Math=Math;
                                        S1_Ave=Ave;
                                        
                                        TotalAve = S1_Ave;
                                }
                                
                                else if (1==NumberOfStudent)
                                {
                                        S2_No = NumberOfStudent + 1;
                                        S2_Kor=Kor;
                                        S2_Eng=Eng;
                                        S2_Math=Math;
                                        S2_Ave=Ave;
                                        
                                        TotalAve = (S1_Ave + S2_Ave)/2;
                                }
                                else
                                {
                                        S3_No = NumberOfStudent + 1;
                                        S3_Kor=Kor;
                                        S3_Eng=Eng;
                                        S3_Math=Math;
                                        S3_Ave=Ave;
                                        
                                        TotalAve = (S1_Ave + S2_Ave + S3_Ave)/3;
                                }
                                
                                NumberOfStudent++;
                                
                                cout << "\n학생 성적이 올바르게 입력되었습니다. \n";
                                
                                break;
                        }
                        
                case '2':
                        {
                                cout << "\n전체 성적 보기 \n";
                                cout << "학번 국어 영어 수학 평균 \n";
                                for (int i = 0; i < NumberOfStudent; ++i)
                                {
                                        if (0==i)
                                        {
                                                cout << S1_No << " " << S1_Kor << " " << S1_Eng;
                                                cout << " " << S1_Math << " " << S1_Ave << "\n";
                                        }
                                        else if (1==i)
                                        {
                                                cout << S2_No << " " << S2_Kor << " " << S2_Eng;
                                                cout << " " << S2_Math << " " << S2_Ave << "\n";
                                        }
                                        else
                                        {
                                                cout << S3_No << " " << S3_Kor << " " << S3_Eng;
                                                cout << " " << S3_Math << " " << S3_Ave << "\n";
                                        }
                                }
                                cout << "\n전체 평균 = " << TotalAve<< "\n";
                                
                                break;
                        }
                case 'q':
                case 'Q':
                        cout << "\n프로그램을 종료합니다. \n";
                        return 0;
                        
                default:
                        cout << "\n올바른 값을 입력해 주세요.\n";
                }
        }
        return 0;
}

1번 눌렀을 때 세 번만 점수 입력 되야 되는데 자꾸 입력되구요.
2번 누르면 점수가 출력되야 되는데 그냥 아무것도 안 나옵니다.
책에서 시키는대로 했는데 이상하네요. 아....

아 그리고 혹시 프로그래밍 언어 질문같은거 할 수 있는 사이트 같은데 없을까요?

복학해서 공부 하는데 원래도 못 했지만 진짜 미치겠네요.. 머리가 그냥 돌인것 같아요......