How to be a game programmer and developer?

[GüntherJung]

Hello :) .I am new in this forum and i am really interested in programming.I really want to learn to program with Cuda, C++ you know. I want to make my own game engines and 3D games with stunning grafiks. I saw really interesting things in the Nvidia developer zone like Nvidia PhysX SDK, OpenGL, OpenCL, DirectX and many other stuff. I want to learn how to program with them and for what and how can i use it? What i must learn first? From what i must start? What book's i must read of i am new to software and game programming? I am really confused. Thank's :D .

[+Nik Louch Subscriber²]

I haven't remembert it.

What? Why?

Like I said... Write a program that takes an input number and counts down to zero from that number!

[Solid Knight]

From what I can tell you've only just begun to grasp the concepts of functions. Although there are other ways of tackling this program to make it smaller and more compact your level of skill is fine for this program.

Some tips:

#1 - Implement one AI for now. Add the other two later.

#2 - Know your data structures, loops, and functions. Read up on all of them. Write simple programs to play around with all the various things they can do.

#3 - Use a two-dimensional array of type char (a type of data structure) instead of a bunch of individual chars. This will allow you to simplify/compact your code.

#4 - Learn how to break your code down into reusable functions. This just takes some thought. For example: a function that checks to see if the game has been won, a function that gets user input, a function for AI, a function that checks for valid moves (either player or AI), et cetera. Think of high-level tasks, like the aforementioned, each one should be in its own function.

[~Johnny]

What? Why?

I believe he means "I haven't copied it [the counting program example], I've just looked at it for the syntax".

[GüntherJung]

Sorry. I will make a new one. This time to make this:

What? Why?

Like I said... Write a program that takes an input number and counts down to zero from that number!

[GüntherJung]

#include <iostream>
using namespace std;
float input;

int main()
{
	cout<<"Input:";
	cin>>input;
	for (int count=input; count>-1; count--) 
	{
    cout << count << ", ";
	}
	cin.get();
	return 0;
}

This should do the work.

[GüntherJung]

#include <iostream>
#include <string>
using namespace std;
char board[8];
char turn='X';
int input;

int main()
{
	for (int moves=0; moves<10; moves++)
	{
		cout<<"|"<<board[0]<<"|"<<board[1]<<"|"<<board[2]<<"|"<<endl;
		cout<<"-------"<<endl;
		cout<<"|"<<board[3]<<"|"<<board[4]<<"|"<<board[5]<<"|"<<endl;
		cout<<"-------"<<endl;
		cout<<"|"<<board[6]<<"|"<<board[7]<<"|"<<board[8]<<"|"<<endl<<endl;
		cout<<"Input:";
		cin>>input;
		turn=board[input];
		if (turn=='X')
		{
			turn='O';
		}
		else
		turn='X';
	}
}

This is the new Tic-Tac-Toe code, but it isn't finished. I have a question for it. When i input something from 0 to 8 it must then update the board, but it don't. And sorry for not using a 2D array. This is because of the:

turn=board[input];

[Andre S. Veteran]

You got that backwards:

board[input] = turn; // this copies the value of turn into the board at position input

[GüntherJung]

I fixed it.

You got that backwards:

board[input] = turn; // this copies the value of turn into the board at position input

Yes when i watched TV and thinked how to fix this i came with this solution.

[Andre S. Veteran]

Ok let me point out a few things you can improve in the code you just posted:

char board[8];

Here the number 8 is not an array index: it specifies the size of the array. Your Tic-Tac-Toe is 9 squares, therefore you should write

char board[9];

Even better, you should use a two-dimensional array, because this more closely models your data:

char board[3][3];

In C++, things are not initialized to "empty" or "zero". In fact, they contain whatever data was in memory before they were created, even if it doesn't make any sense. So you have to initialize your board data, otherwise it will initially contain random data.

	char board[3][3] = {
		{ ' ', ' ', ' ' },
		{ ' ', ' ', ' ' },
		{ ' ', ' ', ' ' }
	}; // declares an 3x3 array and initialize it to contain space characters.

Ok next.

for (int moves=0; moves<10; moves++)

This is incorrect. A game of Tic-Tac-Toe may take a variable number of moves, not necessarily 10. Therefore, a for loop is not appropriate, since for loops are only good when you know how many times you want to loop. Instead, use a while loop:

bool gameOver = false;

while (!gameOver) // while the game is not over
{
    // play a turn
    // if one player won, say
    // gameOver = true;
    // this will break the loop on the next iteration
}

Next.

                cout<<"|"<<board[0]<<"|"<<board[1]<<"|"<< board[2]<<"|"<<endl;
                cout<<"-------"<<endl;
                cout<<"|"<<board[3]<<"|"<<board[4]<<"|"<< board[5]<<"|"<<endl;
                cout<<"-------"<<endl;
                cout<<"|"<<board[6]<<"|"<<board[7]<<"|"<< board[8]<<"|"<<endl<<endl;

This can be written much more concisely with a for loop (I'll let you do that as an exercice). Imagine trying to print a board of an arbitrary size, say, 20x20. Are you going to copy that code 20 times? How many errors would you make doing so? Copy-pasting code is a big no-no. Anytime you find yourself writing the same thing over and over, think how you could write it only once and use loops, functions or data structures to automate the repetition for you.

[Solid Knight]

And sorry for not using a 2D array. This is because of the:

turn=board[input];

int row;
int col;
cout << "\n Row: ";
cin >> row;
cout << "\n Column: ";
cin >> col;

gameBoard[row][col] = turn;

There are ways to improve this but this is the simplest to understand.

[GüntherJung]

There is a reason to use the for loop by my program. And i don't use a 2D array, because of the construction of the code. And i use board[8], because it has 9 values in it, because it starts from 0 and ends with 8 like board[0] to board[8].For the board i find the idea for making it with a loop interesting. This will make the code cleaner an faster. For now i haven't used a loop for the board, but i will. Now i will show you the source code. It works really good. I don't tracked bugs in it. This is the code without AI. And it's just 36 lines of code :) . I think the checking for who wins isn't really good made.

#include <iostream>
#include <string>
using namespace std;
char board[8];
char turn='X';
int input;

int main()
{
	for (int moves=0; moves<10; moves++)
	{
		cout<<"|"<<board[0]<<"|"<<board[1]<<"|"<<board[2]<<"|"<<endl;
		cout<<"-------"<<endl;
		cout<<"|"<<board[3]<<"|"<<board[4]<<"|"<<board[5]<<"|"<<endl;
		cout<<"-------"<<endl;
		cout<<"|"<<board[6]<<"|"<<board[7]<<"|"<<board[8]<<"|"<<endl<<endl;
		input:
		cout<<"Input:";
		cin>>input;
		if(input!=0||input!=1||input!=2||input!=3||input!=4||input!=5||input!=6||input!=7||input!=8)
			goto input;
		if(board[input]=='X'||board[input]=='O')
			goto input;
		board[input]=turn;
		if (turn=='X')
		{
			turn='O';
		}
		else
		turn='X';
	}
	if(board[0]=='X'&&board[1]=='X'&&board[2]=='X'||board[3]=='X'&&board[4]=='X'&&board[5]=='X'||board[6]=='X'&&board[7]=='X'&&board[8]=='X'||board[0]=='X'&&board[3]=='X'&&board[6]=='X'||board[1]=='X'&&board[4]=='X'&&board[7]=='X'||board[2]=='X'&&board[5]=='X'&&board[8]=='X'||board[0]=='X'&&board[4]=='X'&&board[8]=='X'||board[2]=='X'&&board[4]=='X'&&board[6]=='X')
		cout<<"Congratulations, X won.";
	if(board[0]=='O'&&board[1]=='O'&&board[2]=='O'||board[3]=='O'&&board[4]=='O'&&board[5]=='O'||board[6]=='O'&&board[7]=='O'&&board[8]=='O'||board[0]=='O'&&board[3]=='O'&&board[6]=='O'||board[1]=='O'&&board[4]=='O'&&board[7]=='O'||board[2]=='O'&&board[5]=='O'&&board[8]=='O'||board[0]=='O'&&board[4]=='O'&&board[8]=='O'||board[2]=='O'&&board[4]=='O'&&board[6]=='O')
		cout<<"Congratulations, O won.";
}

int row;
int col;
cout << "\n Row: ";
cin >> row;
cout << "\n Column: ";
cin >> col;

gameBoard[row][col] = turn;

There are ways to improve this but this is the simplest to understand.

Good idea, but 2 inputs for just one move? And i thinked to make it in this way, but there are some reasons why.

[GüntherJung]

There is a bug. I will not work until you delete the:

if(input!=0||input!=1||input!=2||input!=3||input!=4||input!=5||input!=6||input!=7||input!=8)
      goto input;

I am thinking why it executes the goto then the if isn't true.

[Andre S. Veteran]

Your program doesn't work at all, and you have no way of knowing other than debugging (which you're probably not familiar with), because the board isn't printed after each move (there's a bug preventing it). If you did, you would see that nothing ever changes on the board. The game continues forever.

This is because one of your goto label "input" has the same name as one of your variables ("input"). For some reason ( I've never seen that one before :blink: ) it screws up the value of that variable, so it's never a valid value. So you just ask for user input indefinitely without ever updating the board.

You could fix it by renaming your goto label, but instead, stop using gotos. You can achieve what you want using a while loop instead. Gotos lead to code that is difficult to understand and modify, and to subtle bugs like what I just described.

And i use board[8], because it has 9 values in it, because it starts from 0 and ends with 8 like board[0] to board[8]

board[8] accesses the 9th value in the array, yes. However, when you declare the array, the number is not an array index. It is the size of the array. You must put 9 there, otherwise your code will crash when you try to access the 9th value.

Think how you could make your "ifs" much, much shorter. Hint: use boolean variables and for loops.

[Andre S. Veteran]

if(input!=0||input!=1||input!=2||input!=3||input!=4||input!=5||input!=6||input!=7||input!=8)

By the way, this condition will always evaluate to true. Can you understand why?

[GüntherJung]

Your program doesn't work at all, and you have no way of knowing other than debugging (which you're probably not familiar with), because you don't print the board after each move. If you did, you would see that nothing ever changes on the board. The game continues forever.

This is because one of your goto label "input" has the same name as one of your variables ("input"). For some reason ( I've never seen that one before :blink: ) it screws up the value of that variable, so it's never a valid value. So you just ask for user input indefinitely without ever updating the board.

You could fix it by renaming your goto label, but instead, stop using gotos. You can achieve what you want using a while loop instead. Gotos lead to code that is difficult to understand and modify, and to subtle bugs like what I just described.

board[8] accesses the 9th value in the array, yes. However, when you declare the array, the number is not an array index. It is the size of the array. You must put 9 there, otherwise your code will crash when you try to access the 9th value.

Think how you could make your "ifs" much, much shorter. Hint: use boolean variables and for loops.

Sorry for this. Now it's fixed. And i fixed it with debugging. I know how to debug.

#include <iostream>
#include <string>
using namespace std;
char board[8];
char turn='X';
int input;

int main()
{
	for (int moves=0; moves<10; moves++)
	{
		cout<<"|"<<board[0]<<"|"<<board[1]<<"|"<<board[2]<<"|"<<endl;
		cout<<"-------"<<endl;
		cout<<"|"<<board[3]<<"|"<<board[4]<<"|"<<board[5]<<"|"<<endl;
		cout<<"-------"<<endl;
		cout<<"|"<<board[6]<<"|"<<board[7]<<"|"<<board[8]<<"|"<<endl<<endl;
		/*for(int boardParts=0; boardParts<10; boardParts++)
		{
			cout<<"|"<<board[boardParts];
		}*/
		input:
		cout<<"Input:";
		cin>>input;
		if(input==0||input==1||input==2||input==3||input==4||input==5||input==6||input==7||input==8)
		{
		}
		else
			goto input;
		if(board[input]=='X'||board[input]=='O')
			goto input;
		board[input]=turn;
		if (turn=='X')
		{
			turn='O';
		}
		else
		turn='X';
	}
	if(board[0]=='X'&&board[1]=='X'&&board[2]=='X'||board[3]=='X'&&board[4]=='X'&&board[5]=='X'||board[6]=='X'&&board[7]=='X'&&board[8]=='X'||board[0]=='X'&&board[3]=='X'&&board[6]=='X'||board[1]=='X'&&board[4]=='X'&&board[7]=='X'||board[2]=='X'&&board[5]=='X'&&board[8]=='X'||board[0]=='X'&&board[4]=='X'&&board[8]=='X'||board[2]=='X'&&board[4]=='X'&&board[6]=='X')
		cout<<"Congratulations, X won.";
	if(board[0]=='O'&&board[1]=='O'&&board[2]=='O'||board[3]=='O'&&board[4]=='O'&&board[5]=='O'||board[6]=='O'&&board[7]=='O'&&board[8]=='O'||board[0]=='O'&&board[3]=='O'&&board[6]=='O'||board[1]=='O'&&board[4]=='O'&&board[7]=='O'||board[2]=='O'&&board[5]=='O'&&board[8]=='O'||board[0]=='O'&&board[4]=='O'&&board[8]=='O'||board[2]=='O'&&board[4]=='O'&&board[6]=='O')
		cout<<"Congratulations, O won.";
	cin.get();
	return 0;
}

The solution was transforming:

if(input!=0||input!=1||input!=2||input!=3||input!=4||input!=5||input!=6||input!=7||input! 
=8) 
      goto input;

to this:

if(input==0||input==1||input==2||input==3||input==4||input==5||input==6||input==7||input==8)
		{
		}
		else
			goto input;

I don't know why it worked. I thing some problem with the != operator? And i has a bug at the end. When i fix all bugs i will post the code.

[Andre S. Veteran]

And i fixed it with debugging. I know how to debug.

Fabulous! Then you can see by yourself, in the debugger, that your board array has only 8 elements in it (indices 0-7), since you don't seem to believe me. ;)

[+Nik Louch Subscriber²]

An empty IF just to get to the opposite result is a bad bad bad practise!

[Solid Knight]

Good idea, but 2 inputs for just one move? And i thinked to make it in this way, but there are some reasons why.

You can always have them input a string then convert each char in the string to an int.

Don't use gotos.

Your empty if is the same as:

if (input <= 8 && input >= 0) { /*do nothing*/ }

which is entirely pointless. If you just want the else statement then check for the else conditions only.

[Eric Veteran]

There is a bug. I will not work until you delete the:

if(input!=0||input!=1||input!=2||input!=3||input!=4||input!=5||input!=6||input!=7||input!=8)
      goto input;

I am thinking why it executes the goto then the if isn't true.

Don't use the same name for the goto label as you are for the variable name. Even if it doesn't cause a flaw it's confusing to look at. :)

if ((input < 0) || (input > 8))
   goto labelName;

Better yet, try to rewrite it without the "goto." It's an evil thing. :)

[GüntherJung]

#include <iostream>
#include <string>
using namespace std;
char board[8],desizion;
char turn='X';
int input;

void assigning()
{
board[0]=' ';
board[1]=' ';
board[2]=' ';
board[3]=' ';
board[4]=' ';
board[5]=' ';
board[6]=' ';
board[7]=' ';
board[8]=' ';
turn='X';
}
int main()
{
	for (int moves=0; moves<9; moves++)
	{
		cout<<"|"<<board[0]<<"|"<<board[1]<<"|"<<board[2]<<"|"<<endl;
		cout<<"-------"<<endl;
		cout<<"|"<<board[3]<<"|"<<board[4]<<"|"<<board[5]<<"|"<<endl;
		cout<<"-------"<<endl;
		cout<<"|"<<board[6]<<"|"<<board[7]<<"|"<<board[8]<<"|"<<endl<<endl;
		/*for(int boardParts=0; boardParts<10; boardParts++)
		{
			cout<<"|"<<board[boardParts];
		}*/
		input:
		cout<<"Input:";
		cin>>input;
		if(input==0||input==1||input==2||input==3||input==4||input==5||input==6||input==7||input==8)
		{
		}
		else
			goto input;
		if(board[input]=='X'||board[input]=='O')
			goto input;
		board[input]=turn;
		if (turn=='X')
		{
			turn='O';
		}
		else
		turn='X';
		if(board[0]=='X'&&board[1]=='X'&&board[2]=='X'||board[3]=='X'&&board[4]=='X'&&board[5]=='X'||board[6]=='X'&&board[7]=='X'&&board[8]=='X'||board[0]=='X'&&board[3]=='X'&&board[6]=='X'||board[1]=='X'&&board[4]=='X'&&board[7]=='X'||board[2]=='X'&&board[5]=='X'&&board[8]=='X'||board[0]=='X'&&board[4]=='X'&&board[8]=='X'||board[2]=='X'&&board[4]=='X'&&board[6]=='X')
		{
			cout<<"Congratulations, X won.";
			break;
		}
		if(board[0]=='O'&&board[1]=='O'&&board[2]=='O'||board[3]=='O'&&board[4]=='O'&&board[5]=='O'||board[6]=='O'&&board[7]=='O'&&board[8]=='O'||board[0]=='O'&&board[3]=='O'&&board[6]=='O'||board[1]=='O'&&board[4]=='O'&&board[7]=='O'||board[2]=='O'&&board[5]=='O'&&board[8]=='O'||board[0]=='O'&&board[4]=='O'&&board[8]=='O'||board[2]=='O'&&board[4]=='O'&&board[6]=='O')
		{
			cout<<"Congratulations, O won.";
			break;
		}
	}
	cout<<"Do you want to continue:";
	cin>>desizion;
	switch (desizion)
		case 'y':
			//assigning();
		case 'Y':
			//assigning();
		default:
			break;
	cin.get();
	return 0;
}

This should comply and work. And the array has 9 elements belive me. It can fill the whole board. And i have a question: There is a function assigning. I think i don't speal it correctly, but it generates a bug when i run it in the switch in the end of the program. Why?

PS: The function isn't complete.

Don't use the same name for the goto label as you are for the variable name. Even if it doesn't cause a flaw it's confusing to look at. :)

if ((input < 0) || (input > 8))
   goto labelName;

Better yet, try to rewrite it without the "goto." It's an evil thing. :)

Yes it's confusing you are right.I think rewriting isn't nessecerly, but renaiming the input from goto input is nessecerly.

[Andre S. Veteran]

And the array has 9 elements belive me. It can fill the whole board.

:laugh: Your program doesn't crash but only because C++ lets you read and write outside the bounds of an array. Actually, try this:

char board[8];

board[20] = 'x'; // impossible! 
cout << board[20]; // yet this works!

and that should probably work! ... but maybe not. Read/write operations outside the bounds of an array are a C/C++ specialty: undefined behavior. It might work, or it might not. It might crash your program or do anything. If you were using a nice language like the aforementionned Smallbasic, the runtime would tell you clearly that you can't do that. C++ is much more evil. It lets you do things that make no sense and doesn't even bother to tell you.

Your array contains 8 elements. :devil:

And i have a question: There is a function assigning. I think i don't speal it correctly, but it generates a bug when i run it in the switch in the end of the program. Why?

You must add a "break;" instruction inside each "case" statement, otherwise execution continues to the next case statement.

[GüntherJung]

:laugh: Your program doesn't crash but only because C++ lets you read and write outside the bounds of an array. Actually, try this:

char board[8];

board[20] = 'x'; // impossible! 
cout << board[20]; // yet this works!

and that should probably work! ... but maybe not. Read/write operations outside the bounds of an array are a C/C++ specialty: undefined behavior. It might work, or it might not. It might crash your program or do anything. If you were using a nice language like the aforementionned Smallbasic, the runtime would tell you clearly that you can't do that. C++ is much more evil.

Your array contains 8 elements. :devil:

You must add a "break;" instruction inside each "case" statement, otherwise execution continues to the next case statement.

I saw how to fix the switch. I forgot the {} betwen the 2 case and default so {2 case and default}. It should look like this. And see deaper in the code. the impossible is possible xD. Ok not what you pointed there, but this:

board[0]

board[1]

board[2]

board[3]

board[4]

board[5]

board[6]

board[7]

board[8]

You can assign the a value. See in the code when you input something and then it assings it X or O. And i have a new better code for the program. I've tested it and it works prety good. I haven't tracked an error.

#include <iostream>
#include <string>
using namespace std;
char board[8],desizion;
char turn='X';
int input;

void assigning()
{
board[0]=' ';
board[1]=' ';
board[2]=' ';
board[3]=' ';
board[4]=' ';
board[5]=' ';
board[6]=' ';
board[7]=' ';
board[8]=' ';
turn='X';
}
int main()
{
	start:
	for (int moves=0; moves<9; moves++)
	{
		cout<<"|"<<board[0]<<"|"<<board[1]<<"|"<<board[2]<<"|"<<endl;
		cout<<"-------"<<endl;
		cout<<"|"<<board[3]<<"|"<<board[4]<<"|"<<board[5]<<"|"<<endl;
		cout<<"-------"<<endl;
		cout<<"|"<<board[6]<<"|"<<board[7]<<"|"<<board[8]<<"|"<<endl<<endl;
		/*for(int boardParts=0; boardParts<10; boardParts++)
		{
			cout<<"|"<<board[boardParts];
		}*/
		input:
		cout<<"Input:";
		cin>>input;
		if(input==0||input==1||input==2||input==3||input==4||input==5||input==6||input==7||input==8)
		{
		}
		else
			goto input;
		if(board[input]=='X'||board[input]=='O')
			goto input;
		board[input]=turn;
		if (turn=='X')
		{
			turn='O';
		}
		else
		turn='X';
		if(board[0]=='X'&&board[1]=='X'&&board[2]=='X'||board[3]=='X'&&board[4]=='X'&&board[5]=='X'||board[6]=='X'&&board[7]=='X'&&board[8]=='X'||board[0]=='X'&&board[3]=='X'&&board[6]=='X'||board[1]=='X'&&board[4]=='X'&&board[7]=='X'||board[2]=='X'&&board[5]=='X'&&board[8]=='X'||board[0]=='X'&&board[4]=='X'&&board[8]=='X'||board[2]=='X'&&board[4]=='X'&&board[6]=='X')
		{
			cout<<"Congratulations, X won.";
			break;
		}
		if(board[0]=='O'&&board[1]=='O'&&board[2]=='O'||board[3]=='O'&&board[4]=='O'&&board[5]=='O'||board[6]=='O'&&board[7]=='O'&&board[8]=='O'||board[0]=='O'&&board[3]=='O'&&board[6]=='O'||board[1]=='O'&&board[4]=='O'&&board[7]=='O'||board[2]=='O'&&board[5]=='O'&&board[8]=='O'||board[0]=='O'&&board[4]=='O'&&board[8]=='O'||board[2]=='O'&&board[4]=='O'&&board[6]=='O')
		{
			cout<<"Congratulations, O won.";
			break;
		}
	}
	cout<<"Do you want to continue:";
	cin>>desizion;
	switch (desizion)
	{		
		case 'y':
			assigning();
		goto start;
		case 'Y':
			assigning();
			goto start;
		default:
			break;
	}
	cin.get();
	return 0;
}

Now i will try to make the AI.

PS: I have tried to make the board with a loop, but i don't know how to add the new lines.

[Andre S. Veteran]

board[0]

board[1]

board[2]

board[3]

board[4]

board[5]

board[6]

board[7]

board[8]

You can assign the a value. See in the code when you input something and then it assings it X or O. And i have a new better code for the program. I've tested it and it works prety good. I haven't tracked an error.

You cannot assign a value. It works BY CHANCE: writing outside the bounds of an array is UNDEFINED BEHAVIOR. What is undefined behavior? It's doing things that compile and run, but don't make any sense in the C++ language. Undefined behavior might:

- Do what you want

- Crash your program

- Introduce subtle bugs

- Format your hard drive

- Dump all your porn to the school printer

- Go back in time and make sure your parents never met each other

In your case, you are LUCKY so it's doing what you want. But instead of pushing your luck, you could just as well write:

char board[9];

And have C++ guarantee to you that this:

board[8] = value;

is, in fact, defined behavior.

[Solid Knight]

char board[9]; gives you array indexes 0 through 8.

char board[8]; gives you array indexes 0 through 7.

Skeptical? Read this: http://www.cplusplus.com/doc/tutorial/arrays/

[GüntherJung]

Oh you are right. I remember. Then why board[8]=value works?

I don't know how to code the AI for this Tic-Tac-Toe. Some advice?