Need help with simple code. Very new to C++

OK, I am very new to C++ so if anything is incorrect or there is an easier way or whatever, please let me know.
Here is some code I wrote just to mess around and try to start a program. I was trying to create a simple menu.

Code:

---

#include <iostream>
using namespace std;

int main()
{
        int Selection;
        cout << "Welcome to BlackJack! Choose an option below to continue:\n";
        cout << "\n";
        cout << "1)New Game\n";
        cout << "2)Restore Game\n";
        cout << "3)Exit\n";
        cout << "\n";
        cout << "Selection: ";
        cin >> Selection;
        switch (Selection)
        {
        case 1:
                system("cls");
                break;
        case 2:
                system("cls");
                break;
        case 3:
                system("cls");
                break;
        default:
                system("cls");
                cout << "Invalid Selection";
                break;
        }
        system("pause");
        return 0;
}

---

As you can see, my 3 cases don't do anything besides clear the screen. I was going to make each case go to another submenu after clearing the screen but I haven't gotten to that yet. What I was trying to figure out is... on my default case, I want to make it return to the beginning and ask for the selection again after displaying it was an Invalid Selection. how can I do this?

Also, I tried making line 13 say:

Code:

---

while(cout << "Selection: ");

---

But that just made the program keep displaying Selection over and over again in an infinite loop? can someone explain why this is please?

Quote:

---

Also, I tried making line 13 say:
Code:
while(cout << "Selection: ");
But that just made the program keep displaying Selection over and over again in an infinite loop? can someone explain why this is please?

---

A while loop tests a condition inside the parentheses and evaluates it to true or false, since its evaluating it to true or false, it expects a boolean expression.

so the following expression

Code:

---

int x = 5;
while(x == 5)
{
  cout << "Hello" << endl;
  x = 6;
}

---

will on only run while x eqals 5.

note that if you put a semi colon after the while loop like you did

Code:

---

while(x == 5);

---

the program will run into an infinite loop as x will always remain 5.
this translates to while x equals five, do nothing!

Also, here is a really simple way of testing for the default case

Code:

---

#include <iostream>
using namespace std;

int main()
{
        int Selection = 0;
        while(Selection < 1 || Selection > 3)
        {
                cout << "Welcome to BlackJack! Choose an option below to continue:\n";
                cout << "\n";
                cout << "1)New Game\n";
                cout << "2)Restore Game\n";
                cout << "3)Exit\n";
                cout << "\n";
       
                cout << "Selection: ";
                cin >> Selection;
       
                switch (Selection)
                {
                case 1:
                        system("cls");
                        break;
                case 2:
                        system("cls");
                        break;
                case 3:
                        system("cls");
                        break;
                default:
                        system("cls");
                        cout << "Invalid Selection\n";
                        break;
                }
        }
        system("pause");
        return 0;
}

---

the line

Code:

---

while(Selection < 1 || Selection > 3)

---

translates to while the selection is less than 1 or greater than 3, do what is inside the curly braces. This code is guaranteed to run once as Selection is assigned to 0 zero in the start and will only execute again if an invalid input is entered.

There are other ways of testing for invalid input, but this is a really simple one.

Hope this helps.

OK Thank you, what my problem was that I didnt understand is that when I put the semi colon after the while loop it would make it an infinite loop

So here is my new updated code and it does what I want it to do pretty much:

Code:

---

#include <iostream>
using namespace std;

int main()
{
        int Selection = 0;
        cout << "Welcome to BlackJack! Choose an option below to continue:\n";
        cout << "\n";
        cout << "1)New Game\n";
        cout << "2)Restore Game\n";
        cout << "3)Exit\n";
        cout << "\n";
        while(Selection < 1 || Selection > 3)
        {
                cout << "Selection: ";
                cin >> Selection;
                switch (Selection)
                {
                case 1:
                        system("cls");
                        break;
                case 2:
                        system("cls");
                        break;
                case 3:
                        system("cls");
                        break;
                default:
                        cout << "Invalid Selection\n";
                        cout << "\n";
                        break;
                }
        }
        system("pause");
        return 0;
}

---

Now the next thing I want to do is make case 1, case 2, and case 3 go to another submenu
I was planning on having New Game go to New Game 1, New Game 2, New Game 3, etc.
and Restore game go to Restore Game 1, Restore Game 2, Restore game 3, etc.
I was wondering if there is a way to make this more oganised by maybe having something like:
newgame(); after the system("cls"); under case 1
restoregame(); after the system("cls"); under case 2
And then having defining what newgame() and restoregame() do at the bottom of the program I think?
I think this is called functions? Sorry I forgot how they work if someone could explain please.
And also sorry for being such a nooby coder ;(

Quote:

---

I was wondering if there is a way to make this more oganised by maybe having something like:
newgame(); after the system("cls"); under case 1
restoregame(); after the system("cls"); under case 2
And then having defining what newgame() and restoregame() do at the bottom of the program I think?
I think this is called functions? Sorry I forgot how they work if someone could explain please.
And also sorry for being such a nooby coder ;(

---

Yep, thats a good way to handle it. A function is basically a group of statements which is executed when called from a certain part in a program.

Here is how you declare a simple function

Code:

---

type name (parameters)
{
  //...do stuff
}

---

So, your new game function could look like this

Code:

---

void NewGame()
{
  //..initialize a new game
}

---

This declares NewGame as a function which returns type void(nothing) and takes nothing as a parameter. Your main() is an example of a function which takes nothing as its parameters and returns and integer.

Then you could call it like this

Code:

---

      case 1:
                system("cls");
                NewGame();
                break;

---

Note: The compiler must be able to see the function declaration before it is called. There are two ways to handle this-

a) define the function before main()
b) declare a function prototype before main and define the function after main.
This basically tells the compiler that the function is defined somewhere in the code even though it is being called earlier in the program. A prototype is declared exactly like the function itself with a semicolon instead of the curly braces.

eg:

Code:

---

void NewGame();

---

This prototype must be placed before the function is called by your program. In your case, before main().

Well here is my new updated progarm:

Code:

---

#include <iostream>
using namespace std;

int newgame();
int restoregame();

int main()
{
        int WelcomeSelection = 0;
        cout << "Welcome to BlackJack! Choose an option below to continue:\n";
        cout << "\n";
        cout << "1)New Game\n";
        cout << "2)Restore Game\n";
        cout << "3)Exit\n";
        cout << "\n";
        while(WelcomeSelection < 1 || WelcomeSelection > 3)
        {
                cout << "Selection: ";
                cin >> WelcomeSelection;
                switch (WelcomeSelection)
                {
                case 1:
                        system("cls");
                        newgame();
                        break;
                case 2:
                        system("cls");
                        restoregame();
                        break;
                case 3:
                        system("cls");
                        break;
                default:
                        cout << "Invalid Selection\n";
                        cout << "\n";
                        break;
                }
        }
        system("pause");
        return 0;
}
int newgame()
{
        int NewGameSelection = 0;
        cout << "Create a game\n";
        cout << "1)New Game 1\n";
        cout << "2)New Game 2\n";
        cout << "3)New Game 3\n";
        cout << "\n";
        while(NewGameSelection < 1 || NewGameSelection > 3)
        {
                cout << "Selection: ";
                cin >> NewGameSelection;
                switch (NewGameSelection)
                {
                case 1:
                        system("cls");
                        break;
                case 2:
                        system("cls");
                        break;
                case 3:
                        system("cls");
                        break;
                default:
                        cout << "Invalid Selection\n";
                        cout << "\n";
                        break;
                }
        }
        return 0;
}
int restoregame()
{
        int RestoreGameSelection = 0;
        cout << "Restore a game\n";
        cout << "1)Restore Game 1\n";
        cout << "2)Restore Game 2\n";
        cout << "3)Restore Game 3\n";
        cout << "\n";
        while(RestoreGameSelection < 1 || RestoreGameSelection > 3)
        {
                cout << "Selection: ";
                cin >> RestoreGameSelection;
                switch (RestoreGameSelection)
                {
                case 1:
                        system("cls");
                        break;
                case 2:
                        system("cls");
                        break;
                case 3:
                        system("cls");
                        break;
                default:
                        cout << "Invalid Selection\n";
                        cout << "\n";
                        break;
                }
        }
        return 0;
}

---

I actually figured it out before you posted that, that's why I am replying so fast in case you were wondering how I coded that so fast LoL.
Anyways...
I don't really get the void thing?
Also, please let me know anything I am doing that is not as efficient or anything as other ways because I am just trying to learn and get better at C++ right now.
Thanks for all your help Spidey by the way, you are really helpful.

Oh OK, so basically instead of having this at the end of my defined function:

Code:

---

return 0;

---

I can just remove that and change the function from int NewGame() to void NewGame()
correct?
Also, in my main function, I do not need the return 0; either because it automatically does it, right?
Alsooo, if I wanted to, I could just declare the functions right after defining them above the int main() instead of declaring them at the bottom of the program?
Sorry for so many questions, I really do appreciate your help tho!

And to define and declare a function about the int main() I can just put it like this without the semicolon:

Code:

---

void NewGame()
{
  // type code here
}

---

Or would I have to do it like this:

Code:

---

void NewGame();
void NewGame()
{
  // type code here
}

---

Quote:

---

Oh OK, so basically instead of having this at the end of my defined function:
Code:
return 0;
I can just remove that and change the function from int NewGame() to void NewGame()
correct?
Also, in my main function, I do not need the return 0; either because it automatically does it, right?
Alsooo, if I wanted to, I could just declare the functions right after defining them above the int main() instead of declaring them at the bottom of the program?
Sorry for so many questions, I really do appreciate your help tho!

---

Correct, you can make it type void and just write

Code:

---

return ;

---

instead of

Code:

---

return 0;

---

You do not need the return 0; in main but it is bad practice not to put it. Some compilers may give you an error about this. If you dont want main to return a value you can declare it as

Code:

---

void main()
{

  return;
}

---

instead.

Yes, if you define your functions above main you do not need the prototype.
like this -

Code:

---

void NewGame()
{
 //... do stuff
}

int main()
{
  NewGame();
  return 0;
}

---

By the way, I don't know why your newgame() is branching into 3 more new games. I'm assuming your trying to write a program which allows you to save and load games stored on disk ?
That is great but since your just starting C++, I would recommend just have one new game and make it start the blackjack program when it is called.
After you've completed that you can add more features and save your data on disk and have the restore game etc.

Quote:

---

Originally Posted by Spidey

If you dont want main to return a value you can declare it as

Code:

---

void main()
{

  return;
}

---

instead.

---

Incorrect. That is not standard C++.

why do you say to have return; instead of return 0;
I tried it without putting return; at all and just completely removing that line and it worked fine?

Yes I know I should start out with having just one game. I was just messing around and trying stuff for practice.
For starting the blackjack game, I don't even know how to assign random cards or anything yet.

Quote:

---

Originally Posted by Tux0r

Incorrect. That is not standard C++.

---

When you say that is not standard C++ do you mean the code won't work or you just mean it is not good form or w\e

Quote:

---

Originally Posted by PersianStyle

When you say that is not standard C++ do you mean the code won't work or you just mean it is not good form or w\e

---

It means you should keep the hell away from it because it's not guaranteed to compile.

Quote:

---

Originally Posted by Tux0r

It means you should keep the hell away from it because it's not guaranteed to compile.

---

well I tried to put return; just to see and it compiled
But I just dont put a return statement at all and remove the line completely.
Is this correct?

Quote:

---

Originally Posted by PersianStyle

well I tried to put return; just to see and it compiled
But I just dont put a return statement at all and remove the line completely.
Is this correct?

---

In a void function you don't have to have a return; if you don't want to. But it can be used to skip out of the function earlier than at the end.

Code:

---

void render(const Model& model) {
    if(model.invisible())
        return;

    model.render();
}

---

Main returning void is no standard C++, so it's not guaranteed to compile (it should never compile, really).
But, PersianStyle, you really lack the very basics of the language. I suggest you get a good book and read it through before you do anything else. I recommend Accelerated C++. There are more good books in the books thread.
Believe me, it will help you a lot to read it before doing anything else.

Quote:

---

Originally Posted by Elysia

Main returning void is no standard C++, so it's not guaranteed to compile (it should never compile, really).
But, PersianStyle, you really lack the very basics of the language. I suggest you get a good book and read it through before you do anything else. I recommend Accelerated C++. There are more good books in the books thread.
Believe me, it will help you a lot to read it before doing anything else.

---

No thanks, I hate reading books LoL
I been learning a lot better this way.

You can give up becoming any decent programmer if you don't read any books, because the code you write is so flawed and your understanding so bad that everyone will have to explain everything you do to you.

I just started programming as well persian... and I have asked alot of dumb questions too. Don't let it get you down. Try using the Lessons page on the main web site for this board, or find an easier to navigate tutorial page. So when you ask yourself how do I declare a function. You look on the page click on the tab that says functions and walaa. You can usually find your answer on the net quicker than someone gives it. I don't read an entire book and then program that would be boring. I learn one new idea/concept from a book or tutorial and then devise a new program to utilize it. Try to stay within your boundries of knowledge and then repitition gets it in your head. If you would like you can email me at [email protected] and I would be happy to help you with questions, but remember part of being a good programmer is being to good problem solver don't look for the answer to fast or you are shortcutting building your problem solving skills.

No matter what anyone says a human being will succeed at what he/she wants through persistant and consistent effort. Henry Ford did not know how to do half the stuff his company did it was surrounding himself with more knowledgable people that got him there.

You may do it the way you want, naturally.
However, books do have advantages. You read a chapter in a book, do the exercises, move on.
When you finish the book, you have a solid understanding of at least the basics. And I mean such things as functions, loops, variables, stuff that is absolutely essential for any program. Making a program without them just isn't possible.
And since it seems the OP doesn't even grasp functions, she/he does indeed need to learn the basics, and books are great for that. Tutorials often cover just a small spectrum of things and many tutorials are just plain wrong.

After having read a book, or while reading a book, that is the time for questions. All the while, you can put your knowledge to use. But not before. And not before knowing the absolute basics.
Say what you will about that. That's the cold hard truth.

I'll add two more things, as well.
Firstly, the forum is more about answering questions than teaching. Most members will simply refer you to books or tutorials if you don't know how, for examples, templates work.
Secondly, it would be frustrating if you run into a dead end in your programming because you don't know how to solve it and find out that if you simply had learned sufficient basics of the language before attempting to write the program, you could easily have solved it.