int main() running constantly - c++

Question

I am brand new to c++ so I apologize if this is a stupid question but I can't seem to find the answer to it.
I have been using Processing for a while now and would like to start using c++ because I heard it is faster and a program I made is too long/dense for Processing to run at a reasonable speed.
In Processing there is a setup void which runs once and then the draw void which runs continuously after that. This is what I am used to and I need it to make remake a program in c++ (a chess AI).
Is there a way to get int main to run continuously? If not can I have it call a function that will run continuously?
Also is there a way to make a window pop up when you run the program which you can draw geometry to? (I will need to make pieces that can be manipulated by a mouse ideally)
I'm using Xcode by the way

Answer 1

main() should typically do your setup and then start the main message-processing loop provided by your toolkit. The message processing loop will run continuously until the user requests your application to quit (or you ask the toolkit to shut down your app).
Your toolkit will call your draw function whenever your window needs to be painted. It will call other functions when user input such as keypresses or mouse clicks happen.
For example, if you were using the GLUT toolkit (for OpenGL, a very popular drawing API supported on Mac, Windows, Linux, and many mobile devices), your main function might look like this (complete tutorial here):
void main(int argc, char **argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DEPTH | GLUT_SINGLE | GLUT_RGBA);
glutInitWindowPosition(100,100);
glutInitWindowSize(500,500);
glutCreateWindow("My First openGL Program");
glutDisplayFunc(render);
glutMainLoop();
}
For Cocoa, the OSX native API, it might look like this (more information and links here):
#import <Cocoa/Cocoa.h>
int main(int argc, const char** argv)
{
return NSApplicationMain(argc, argv);
}

Answer 2

May I suggest that instead of asking very rudimentary questions like this on StackOverflow, you go and invest your time reading one of the thousands of introductory C++ tutorials that are scattered all over the web.
After a couple of hours of reading you'll find that questions like this are answered faster via a Google search.
Good luck with your learning.

Answer 3

You should not try to get main() to run continuously.
You may instead do something like this:
int main() {
while (true) {
//call functions here
}
return 1;
}

Answer 4

In C++, each function is defined by it's call and it's return. For example:
void foo()
{
cout << "hello world!";
return;
}
int main()
{
foo();
return 0;
}
When foo() is called, it runs until the return statement. If we want foo to run for some indeterminate amount of time, we could, for example:
void foo()
{
bool isExiting = false;
char input;
while( isExiting != true )
{
cout << "Exit? ";
cin >> input;
if ( input == 'y' )
{
isExiting = true;
}
return;
}
}
int main()
{
foo();
return 0;
}
This is a kind of ugly example - using cin to a char and whatnot - but it gets the idea across. The while loop will run forever and the innards of it (well, it's logic, anyway) could be replaced with whatever your program needed to do.
Make sense?

Answer 5

There are plenty of options as far as graphics libraries go; you can use SDL, GLUT/OpenGL, DirectX, even good ol' Win32. However, for someone who is relatively new to things as rudimentary as while loops, I suggest that you stay off the C++ for a while, as there are many peculiarities that might prove to be enormous roadblocks. If you really need every ounce of speed, I recommend that you make a DLL with your time-critical algorithms and use it in conjunction with a simpler language that supports DLL's, and provides a relatively developer-friendly interface. Game Maker comes immediately to mind, although I'm sure there are many options out there.
Best of luck.

Answer 6

I'd recommend having a look at Cinder or OpenFrameworks as a neat transition from Processing.org - especially if you're planning on doing multimedia applications (which, if you were using Processing, is likely)
They both provide a very similar layer to that of Processing, and will ease your journey somewhat.
You could also implement your own basic framework on top of SDL if you feel up to it.
As a more general answer to your question, the main() function is basically the same as the setup() function in Processing.org - with the main distinction being that it has to call a (user-provided) draw() function or equivalent.
So a rudimentary equivalent would be:
bool quit = FALSE;
void setup() {
// initialise the screen and so forth
}
void draw() {
// perform some drawing and update tasks
}
int main(int argc, char *argv[]) {
setup();
while (!quit) {
draw();
}
shutdown();
return 0;
}
NB: the above will probably compile, but it would do nothing except loop and potentially bog up your machine since it's not connected to any graphics library and is getting no user input to modify the quit boolean.
finally, I'll quote a section from the Cinder faq:
I’m experienced with Processing, but I
think I’m ready to try something new.
Is Cinder right for me?
Very possibly.
First though, be sure you really need
to move on to Cinder. Have you already
experimented with using an external
IDE like Eclipse? Are you using native
OpenGL calls instead of PGraphics?
What about experimenting with Toxi’s
excellent libraries? You’ll learn some
things that will make an eventual
transition to Cinder much easier, and
as much as we’re into C++, it’s easy
to underestimate how far Processing
can take you. All that said, don’t let
us talk you out of this either — if
you’re excited about learning Cinder,
we’re excited to have you, and we bet
you’ll find it’s easier to get started
than you might imagine.