case bypasses initialization

#include <iostream.h>
#include <stdio.h>
#include <conio.h>

main()
{
				int input, input2;
            int tugas[100], uts[100], uas[100];
            double nilaiakhir[100];
         		char nim[12];
            	char nama[50];
              	char mk[50];;



   do {
   	cout<<" menu : ";
   	cout<<"\n 1. input data mahasiswa";
   	cout<<"\n 2. pilihan 2";
   	cout<<"\n 3. keluar";
   	cout<<" masukan angka : ";
   	cin>>input;

		switch (input)
      {
      case 1:
   		cout<<" menu : ";
   		cout<<"\n ========================================";
     	 	cout<<"\n        Input Data Nilai Mahasiswa       ";
      	cout<<"\n ========================================";
         cout<<"\n Jumlah Data Mahasiswa : ";

      	cin>>input2;


         for (int i = 0 ; i < input2; i ++){
         cout<<"\n Data ke"<<input2;
         cout<<"\n masukan nim : ";
         cin>>nim[i];
         cout<<"\n masukan nama ";
         cin>>nama[i];
         cout<<"\n Masukan Mata kuliah : ";
         cin>>mk[i];
         cout<<"\n Masukan Nilai Tugas : ";
         cin>>tugas[i];
         cout<<"\n masukan Nilai UTS : ";
         cin>>uts[i];
         cout<<"\n masukan Nilai UAS : ";
         cin>>uas[i];

         nilaiakhir[i] = (0.4 * tugas[i]) + (0.3 * uts[i]) + (0.3 * uas[i]);
         if (nilaiakhir[i] >=0 && nilaiakhir[i] <= 54){
         	cout<<"\nNilai Huruf : E";
         }
         else if (nilaiakhir[i] >=55 && nilaiakhir[i] <= 59){
         	cout<<"\nNilai Huruf : D";
         }
         else if (nilaiakhir[i] >=55 && nilaiakhir[i] <= 59){
         	cout<<"\nNilai Huruf : C";
         }
         else if (nilaiakhir[i] >= 60 && nilaiakhir[i] <= 64) {
            cout<<"\nNilai Huruf : C+";
         }
         else if (nilaiakhir[i] >= 65 && nilaiakhir[i] <= 74) {
            cout<<"\nNilai Huruf : B";
         }
         else if (nilaiakhir[i] >= 75 && nilaiakhir[i] <= 79) {
         cout<<"\nNilai Huruf : B+";
         }
         else if (nilaiakhir[i] >= 80 && nilaiakhir[i] <= 100) {
         cout<<"\nNilai Huruf : A";
         }
         }
       break;

  		case 2:
   		cout<<"test";
         cout<<"\n========================================";
         cout<<"\n Data Nilai Akhir dan Huruf Mahasiswa  ";
         cout<<"\n========================================";
         cout<<"\n  Berapa Jumlah Data yang ingin di tampilkan ?? ";
         cin>>input2;
         int input3 = input2;

         for (int j = 0; j<input3; j++){
         int k = 1+j;
         cout<<k<<".";
         cout<<"\nNim : "<<nim[j];
         cout<<"\nNama : "<<nama[j];
         cout<<"\nNama Matkul : "<<mk[j];
         cout<<"\nNilai Akhir : "<<nilaiakhir[j];
         }
      break;

   	default:
   		cout<<"Terima kasih, tekan 'ENTER' untuk keluar program";
         break;
         }
   }
   while (input < 3);
   cout<<"Terima kasih, tekan 'ENTER' untuk keluar program";
}