I'd like to know if it makes sense to know assembler nowadays? or I should forget it as wasting of time? When I've learnt some basics like reading files counting, making loop and function.
I'm not sure if it makes sense to learn more? can I ever needed?
Dupe: http://stackoverflow.com/questions/143561/is-there-a-need-to-use-assembly-these-days
Assembler is still used in alot of embeded devices and micro chips. I don't think its widely used on PCs anymore, but it does let you write efficent code.
I rarely write assembly nowadays.
However, I still read assembly quite a bit. Assembly is incredibly useful in debugging native code - following optimized code can be very difficult, with local values containing seemingly random data and the currently executing instruction jumping randomly throughout a function. The disassembly doesn't lie and can give you much better insight into what is happening.
IMHO, It makes sense to have at least tried it because knowing it makes it much easier to understand how things works beyond the compiler step. Just the tiny bits and pieces that people without the knowledge of things like "registers" just have a hard time to get.
Personally I still use some assembler now and then but in a cross platform world I really try to stay away from it unless it is absolutely needed or just for fun :-)
I don't think there is any reason to use assembly except perhaps in really low-level device drivers or embedded systems. There is, however, much value in knowing assembly, even if you don't use it. It's a great way to learn about the nitty-gritty details of your platform of choice, which is invaluable in some circumstances (even though it would be abstracted away in an ideal world, it does have practical implications that cut through the abstractions).
Even if you never use Assembly in practice, learning it is an excellent way to understand how the hardware works, and how high-level code is translated into machine code and executed. It will teach you about CPU registers, memory segmentation, integer and floating point representation, etc.
Assembler is still used for some games, to eke out some more performance, from what I understand, and, as was mentioned, doing dsp work will lead to needing assembler.