Tugas Dasar Dasar Pemrograman kalkulator sederhana

source code :
#include <iostream.h>
#include <stdlib.h>
#include <iomanip.h>
#include <string.h>
#include <math.h>
#include <conio.h>
//#include <cstdlib>
//#include <iostream>
//#include <math.h>
//#include <string>
using namespace std;

class calc
{
  friend ostream & operator << ( ostream &, const calc & );
  friend istream & operator >> ( istream &, calc & );

public:
  void menu();
  void tambah();
  void kurang();
  void kali();
  void bagi();
  void input();
  void input1();
  void pilihan1();
  void pilihan2();
  void sines();
  void cosines();
  void tangen();
  void logku();
  void sqrtku();
  void expku();
private:
  int pilih, pilih1, pilih2, pilih4;
  char pilih3, pilih5;
  float a;
  float b;
  float c;
  float hasil;
  float hasil1;
};
void calc::menu()
{
  cout << endl;
  cout << " \t\t\t+================================+ " << endl;
  cout << " \t\t\t|      CALCULATOR SEDERHANA      | " << endl;
  cout << " \t\t\t|                                | " << endl;
  cout << " \t\t\t|           Wisnu.Nugroho        | " << endl;
  cout << " \t\t\t|            10018134            | " << endl;
  cout << " \t\t\t|                C               | " << endl;
  cout << " \t\t\t+================================+ " << endl;
  cout << endl;
  cout << endl;
  cout << " +-----------------------------------------------------+ " << endl;
  cout << " | [ 1 ] Menu Pilihan operator Matematika              | " << endl;
  cout << " |       --> [+][-][:][*]                              | " << endl;
  cout << " | [ 2 ] Menu Pilihan fungsi-fungsi matematika         | " << endl;
  cout << " |       --> [Sin][Cos][Tan][log][Sqrt][exp]           | " << endl;
  cout << " | [ 0 ] Keluar program                                | " << endl;
  cout << " +-----------------------------------------------------+ " << endl;
  cout << endl;
  cout << "Masukan pilihan : ";
  cin >> pilih1;
  cout << endl;

  if ( pilih1 == 1 )
  {
    pilihan1();
  }
  else if ( pilih1 == 2 )
  {
    pilihan2();
  }
  else if ( pilih1 == 0 )
  {
    exit( 0 );
  }
}

void calc::pilihan1()
{


  cout << "Oparator Matematika" << endl;
  cout << "1. Tambah (+)" << endl;
  cout << "2. Kurang (-)" << endl;
  cout << "3. Kali   (*)" << endl;
  cout << "4. Bagi   (:)" << endl;
  cout << endl;
  cout << "Masukkan No Oparator yang anda inginkan : ";
  cin >> pilih2;


  if ( pilih2 == 1 )
  {
    tambah();
  }
  else if ( pilih2 == 2 )
  {
    kurang();
  }
  else if ( pilih2 == 3 )
  {
    kali();
  }
  else if ( pilih2 == 4 )
  {
    bagi();
  }
  else
  {
    cout << "Oparator yang anda masukkan salah ";
  }
}

void calc::pilihan2()
{

  cout << "Oparator fungsi-fungsi matematika" << endl;
  cout << "1. Sin   " << endl;
  cout << "2. Cos   " << endl;
  cout << "3. Tan   " << endl;
  cout << "4. log   " << endl;
  cout << "5. sqrt  " << endl;
  cout << "6. exp   " << endl;
  cout << endl;
  cout << "Masukkan No Oparator yang anda inginkan : ";
  cin >> pilih4;

  if ( pilih4 == 1 )
  {
    sines();
  }
  else if ( pilih4 == 2 )
  {
    cosines();
  }
  else if ( pilih4 == 3 )
  {
    tangen();
  }
  else if ( pilih4 == 4 )
  {
    logku();
  }
  else if ( pilih4 == 5 )
  {
    sqrtku();
  }
  else if ( pilih4 == 6 )
  {
    expku();
  }
  else
  {
    cout << "Operator yang anda masukkan salah " << endl;
  }

}

void calc::input()
{
  cout << "Masukkan bilangan pertama :";
  cin >> a;
  cout << "Masukkan bilangan kedua   :";
  cin >> b;
}

void calc::tambah()
{
  input();

  hasil = a + b;
  cout << "Hasilnya adalah  : " << hasil << endl;
  cout << endl;
}

void calc::kurang()
{
  input();

  hasil = a - b;
   cout << "Hasilnya adalah  : " << hasil << endl;
  cout << endl;
}

void calc::kali()
{
  input();
  hasil = a * b;
   cout << "Hasilnya adalah  : " << hasil << endl;
  cout << endl;
}

void calc::bagi()
{
  input();
  hasil = a / b;
   cout << "Hasilnya adalah  : " << hasil << endl;
  cout << endl;
}


void calc::input1()
{
  cout << "Masukkan bilangan:";
  cin >> c;

}

void calc::sines()
{
  input1();
  hasil1 = sin( c );
  cout << "Hasilnya adalah  : " << hasil << endl;
  cout << endl;
}

void calc::cosines()
{
  input1();
  hasil1 = cos( c );
  cout << "Hasilnya adalah  : " << hasil << endl;
  cout << endl;
}

void calc::tangen()
{
  input1();
  hasil1 = tan( c );
  cout << "Hasilnya adalah  : " << hasil << endl;
  cout << endl;
}

void calc::logku()
{
  input1();
  hasil1 = log( c );
  cout << "Hasilnya adalah  : " << hasil << endl;
  cout << endl;
}

void calc::sqrtku()
{
  input1();
  hasil1 = sqrt( c );
  cout << "Hasilnya adalah  : " << hasil << endl;
  cout << endl;
}

void calc::expku()
{
  input1();
  hasil1 = exp( c );
  cout << "Hasilnya adalah  : " << hasil << endl;
  cout << endl;
}

main()
{
  calc wisnu;
  wisnu.menu();

    system("PAUSE");
    return EXIT_SUCCESS;
}