vprasanje c++

 #include <iostream.h>
using namespace std;

int main ()
{         
          while (true)
     {
          system ("CLS");
          cin.clear ();
    int n;   
    std::string racunanje;
    std::string stojan;
    cout << "Kaj zelite delati?" << endl;
    cout << "- Racunanje" << endl;
    cout << "- Stojan" << endl;
    cin >> racunanje >> stojan;
    if (racunanje == "Racunanje")
    {
                    while (true)
     {
          system ("CLS");
          cin.clear ();
    cout << "Program vam izracuna veckotnik" << endl;
    cout << "Vpisite stevilo" << endl;
    cin >> n;
    cout << "Trikotnik ima " << n * (n - 3) / 2 << " stranic" << endl;
    system ("pause");
    if (stojan == "Stojan")
    cout << "Vpisite kodo" << endl;
    }
    }
    else
    cout << "Napaka" << endl;
    system ("pause");
    }
    return 0;
}
  

int main(int argc, char* argv[])
{

	while (true)
	{
		system ("CLS");
		cin.clear ();
		int n;
		int izbira1, izbira2;

		/* meni izbire */
		cout << "Kaj zelite delati? Izberi stevilko" << endl;
		cout << "1. Racunanje" << endl;
		cout << "2. Stojan" << endl;
		cin >> izbira1;

		if (izbira1 == 1) // racunanje
		{
			while (true)
			{
				system ("CLS");
				cin.clear ();
				cout << "Program vam izracuna veckotnik" << endl;
				cout << "Vpisite stevilo: ";
				cin >> n;
				cout << "Trikotnik ima " << n * (n - 3) / 2 << " stranic" << endl;

				/* meni izbire */
				cout << "Koncaj racunanje?" << endl;
				cout << "1. Da" << endl;
				cout << "2. Ne" << endl;
				cin >> izbira2;
				if (izbira2 == 1)
					break;
			}
		}
		else if (izbira1 == 2) // stojan
		{
			cout << "Vpisite kodo" << endl;
			/*tuki se neki manka*/
		}
		else // napaka
		{
			cout << "Napaka" << endl;
		}

		system ("pause");
	}
    return 0;
}

int main(int argc, char* argv[])
{
    int odg;
    do {
        cout<<endl;
        cout<<"1. Racunanje"<<endl;
        cout<<"2. Stojan"<<endl;
        cout<<"0. Izhod"<<endl;
        cout<<"Vnesi izbiro: ";
        cin>>odg;
        
        switch(odg)
        {
        case 1: 
             
                system ("CLS");
		cin.clear ();
		int n;
		cout << "Program vam izracuna veckotnik" << endl;
		cout << "Vpisite stevilo: ";
		cin >> n;
		cout << "Veckotnik ima " << n * (n - 3) / 2 << " stranic" << endl;
		cout<<endl;
		break;
				
         case 2: 
        	cout << "Vpisite kodo" << endl;
		/*tuki se neki manka*/
		break;
			
			
         case 0: 
              cout<<endl;
              cout<<"Program se bo zakljucil\n";
              break;
              
         default: 
                  cout<<endl;
                  cout<<"Ponovite izbiro"<<endl;
                  break;
                  
         }
         } while(odg!=0);
         
         //Raje kot system("PAUSE"); uporabi nekaj takega
         cin.ignore();
         cin.get();
         
         return 0;
         
}

char Obrni(char niz[])
{
	int k=strlen(niz);

	for(int i=k; i >= 0;i--)
	{
	cout<<niz[i];
	}
}

int main()
{
	char niz[]= "Dobro jutro, C++!";
	cout <<  niz <<endl;
	Obrni(niz);
	cout<<endl;

	return 0;
} 

void obrni (char *niz)
{
	int j = strlen (niz) - 1;
	int i = 0;
	while (j > i)
	{
		char ch = niz [i];
		niz [i] = niz [j];
		niz [j] = ch;
		--j;
		++i;
	}
}


int main(int argc, char* argv[])
{
	char niz [] = "Dobro jutro, C++!";
	cout << niz << endl;
	obrni (niz);
	cout << niz << endl;

	return 0;
}