Is it safe to do so? If not why it isn't?

a lil more info man.. what are u wanting to do ?

You should shut down your OS properly before switching it off at the mains. If you don't then it can be bad news for your hard disk.

my desktop back home is set to shut down properly when the shutdown button is pressed. r u talking about something like this or instantly closing the computer with the button?

if second then: all your unsaved stuff will be gone. after a while your hdd will get corrupt files. i'm sure there are plenty of reasons
but the question is why would u want that?

maybe soem of u didn't read the topic that's why u didn't got it clear. Anyway I'm just curious . Thanks for the replies

???? if u could be more explanative I'm sure u'll find ppl that'll help u.
main switch? what main switch. what is this, a computer? how many switches does it have?

still I couldn't understand do these previous posts answer u or what???

Go to your Control Panel and choose Power Options.
Select the Advanced tab.
Under "Power buttons" you can choose what happens when you press the power button on your computer. It's probably already set to shut down, but it's a good idea to make sure before you start wantonly shutting down your machine.
NOTE: Some motherboards simply don't support this feature. If you don't have "Power buttons" in your Advanced tab, and feel comfortable poking around your BIOS, you can see if you can enable this feature in BIOS. But you may just be out of luck due to your motherboard -- sorry!
If it's not set to shut down, choose that item from the drop-down list.
Now you're ready to shut your computer off. Just hit the power button. Don't touch the keyboard, and keep your hands off that mouse. It's perfectly safe to shut down your computer with the touch of a button. Enjoy!