Bubble sort with array implementation

#include <iostream>
#include <windows.h>
using namespace std;

int batas,menu,data[50];
char ulang;
void Ascending(){
    cout << "Data setelah diurutkan : \n";
    for (int a=0;a<batas;a++){
        for (int b=a+1;b<batas;b++){
            if (data[a]>data[b]){
                int baru;
                baru = data[a];
                data[a]=data[b];
                data[b]=baru;
            }
        }
    }
    for (int d=0;d<batas;d++){
        cout <<" "<<data[d];
    }
}
void Descending(){
    cout << "Data setelah diurutkan : ";
    for (int a=0;a<batas;a++){
        for (int b=a+1;b<batas;b++){
            if (data[a]<data[b]){
                int baru;
                baru = data[a];
                data[a]=data[b];
                data[b]=baru;
            }
        }
    }
    for (int d=0;d<batas;d++){
        cout <<" "<<data[d];
    }
}
int main()
{
    do {
       cout << "Data sebelum diurutkan : \n";
        for (int i=0;i<batas;i++){
            cout <<" "<<data[i];
    }
    cout <<endl;
    cout << "Pilih menu : \n";
    cout << "1. Input data\n";
    cout << "2. Urut Ascending\n";
    cout << "3. Urut Descending\n";
    cout << "4. EXIT\n";
    cout << "Pilihan Anda : ";
    cin >> menu;
    if (menu == 1){
        cout << "Masukkan batas data : ";
        cin >> batas;
        for (int a=0;a<batas;a++){
            cout << "Masukkan Data ke - "<<a+1<<": ";
            cin >> data[a];
        }
    }
    else if (menu == 2){
        Ascending();
    }
    else if (menu == 3){
        Descending();
    }
    else {
        system ("pause");
    }
    cout << "\nIngin ulang lagi ? (y/n)";
    cin >> ulang;
    system("cls");
    }while(ulang == 'y' || ulang == 'Y');
}