Program penjualan barang dengan fungsi

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

char nama[20];
int harga, jml;

int total, tb, byr;
float diskon, kembali, dp;


menu();
komputer();
keyboard();
mouse();
main()
{
menu();
}


menu()
{

       int pil;
       char ulang;
       ulang='y';

      do
      {
          clrscr();
         cout<<"*************************************"<<endl;
         cout<<"<<< MENU UTAMA >>>"<<endl;
          cout<<"1. Komputer"<<endl;
         cout<<"2. Keyboard"<<endl;
         cout<<"3. Mouse"<<endl;
         cout<<"Masukkan Pilihan Anda [1 ,2 ,atau 3] : ";cin>>pil;
         cout<<"*************************************"<<endl;

         if(pil==1)
         {
         komputer();
         }
         else if(pil==2)
         {
         keyboard();
         }
         else if(pil==3)
         {
         mouse();
         }

         else {
         cout<<"pilihan yang anda masukkan salah!"<<endl;
         }


      cout<<"\n\n\n\nmau mengulang ? "<<endl;
      cout<<"tekan Y atau y untuk YA"<<endl;
      cout<<"tekan T atau t untuk TIDAK"<<endl;
      cout<<"tentukan pilihan anda SEKARANG : ";
      cin>>ulang;
      }
      while ((ulang=='Y') || (ulang=='y'));
      return 0;
}


komputer()
{
clrscr();
            cout<<"* Nama Barang : Komputer "<<endl;
         harga = 650000;
         cout<<"* Harga = Rp 650.000,-";
         cout<<"\n* Jumlah Barang = ";cin>>jml;
         total = jml * harga;
             cout<<"\n* Total Harga = "<<jml*harga;
         if (total>800000)
         {
             diskon = 0.15;
             cout<<"\nDiskon = 15%";
         }
         else if (total>700000)
         {
             cout<<"\nDiskon = 10%";
         diskon = 0.1;
     }
         else
         {cout<<"\nDiskon = 0";
         diskon=1;
         }
         dp=total*diskon;
         cout<<"\nDiskon Rupiah = "<<dp;
         tb=total-dp;
         cout<<"\n***************************";
         cout<<"\nTotal Bayar = "<<tb;
         cout<<"\nYang Dibayar = ";cin>>byr;
         kembali=tb-byr;
         cout<<"\n***************************";
         cout<<"\nKembalian = "<<kembali;


return 0;
}


keyboard()
{
clrscr();
            cout<<"* Nama Barang : Keyboard "<<endl;
         harga = 35000;
         cout<<"\n* Harga = Rp 35.000,-";
         cout<<"\n* Jumlah Barang = ";cin>>jml;
         total = jml * harga;
             cout<<"\n* Total Harga = "<<jml*harga;
         if (total>800000)
         {
             diskon = 0.15;
             cout<<"\nDiskon = 15%";
         }
         else if (total>700000)
         {
             cout<<"\nDiskon = 10%";
         diskon = 0.1;
     }
         else
         {cout<<"\nDiskon = 0";
         diskon=1;
         }
         dp=total*diskon;
         cout<<"\nDiskon Rupiah = "<<dp;
         tb=total-dp;
         cout<<"\n***************************";
         cout<<"\nTotal Bayar = "<<tb;
         cout<<"\nYang Dibayar = ";cin>>byr;
         kembali=tb-byr;
         cout<<"\n***************************";
         cout<<"\nKembalian = "<<kembali;


return 0;
}

mouse()
{  clrscr();
            cout<<"* Nama Barang : Mouse "<<endl;
         harga = 15000;
         cout<<"\n* Harga = Rp 15.000,-";
         cout<<"\n* Jumlah Barang = ";cin>>jml;
         total = jml * harga;
             cout<<"\n* Total Harga = "<<jml*harga;
         if (total>800000)
         {
             diskon = 0.15;
             cout<<"\nDiskon = 15%";
         }
         else if (total>700000)
         {
             cout<<"\nDiskon = 10%";
         diskon = 0.1;
     }
         else
         {cout<<"\nDiskon = 0";
         diskon=1;
         }
         dp=total*diskon;
         cout<<"\nDiskon Rupiah = "<<dp;
         tb=total-dp+1;
         cout<<"\n***************************";
         cout<<"\nTotal Bayar = "<<tb;
         cout<<"\nYang Dibayar = ";cin>>byr;
         kembali=tb-byr;
         cout<<"\n***************************";
         cout<<"\nKembalian = "<<kembali;



return 0;
}