I request Gurus how do they manage while coding that no combination, situation or an eventuality skips their eyes.

I generally try to achieve this by extremely incremental developing and testing. I never develop the code for an entire project and then try to debug it. I always write small sections or blocks, 5-20 lines, at a time and then test them.

Testing such small sections of code lets you thinking of (almost) everything that can go wrong with THAT section of code and account for it. You quickly test it and know it works; if it breaks, it's still fresh in your mind.

I've found that this lets me write software that is much more rebust, in my opinion, than if I tried to write an entire project and then go back and debug it. If your blocks are small enough and your incremental testing thorough enough I think you'll find you catch as many bugs as you can reasonably expect to catch.

Regards,
Craig Steiner