I have this recurring (read annoying) problem with Turbo C++. I've a program which uses graphics, and for some reason, the minute I run the program, it exits TC with a dialog box saying:
"This program has performed an illegal operation and has to exit."
The illegal operation on inspection was a general protection fault.
But the frustrating part is, initially when I ran the program, it gave me no problems. When I tried running it the next day, it would keep exiting giving me the error I mentioned above and since then just doesn't work. I tried running it on a friend's PC, doesn't work there either. But it works fine in my college laboratory, and I've no clue how.
I can't figure out if this has to do with my OS or TC itself. Now, basic graphics programs of drawing a line won't work either.
Can someone please help me out here. My program's a standard c++ program which uses a plethora of basic graphics functions like line(), arc() etc.

It sounds suspiciously like a memory problem such as a dangling pointer. They can be incredibly difficult to debug because sometimes everything works fine and sometimes it crashes miserably. Before you blame your system or the compiler, make sure your code is perfect. Otherwise you're showing nothing but arrogance in assuming that you can code no wrong.

Well, I guess I should get a bit verbose about the problem exactly.
Like I said my program worked fine. It had numerous calls to line(), arc(), circle() and a couple of other graphics functions. I started to code a new function and when I ran it, it exited. So I used breakpoints to figure out where
the problem occurred. I realised it exited at a call to arc() in my new function.
The sequence of calls being:
line();
arc();
arc();
arc();
It exited at the very first arc() call.
So I commented all the arc() calls following the line() call. The program worked fine. I couldn't figure out what the problem was, so I sent it to a friend to see if he could. But the program didn't work on his PC even if he commented the arc() calls. That was strange, but after some poking around with the program, we decided to leave it at it.
The next day when I try to run my program again, it doesn't run. Whether I comment the arc() calls, comment the whole new function or just use a few line() functions to draw a couple of lines. Nothing works. But other programs in TC not involving graphics, work just fine.

So then I take it to my college laboratory and what do you know, it works-just fine! No crashes at all.
I reinstalled TC, it still didn't solve the problem. Which is why, I was moved to wonder, if it was just TC or my OS. If I don't figure out the problem, I'd have stick to working in college, which can be cumbersome.
I'm sorry for the verbiage, but hope it explains my situation better.

>but hope it explains my situation better.
That doesn't change my answer at all. A floating error is almost always some variant of memory corruption on your part.