Bitwise Operators and WHY we use them
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- Опубликовано: 6 июл 2024
- Bitwise operators are one of the least understood parts of programming when you are first starting out. In this video, I cover what they are and why we use them!
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⏳ TIMESTAMPS
00:00 Introduction
00:43 Why do we use Bitwise Operators?
01:55 Unix file permissions
02:54 6 Bitwise Operators
03:01 AND Operator
04:08 OR Operator
05:17 XOR Operator
06:01 NOT Operator
06:30 Negative Numbers
07:24 Left Shift and Right Shift
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I’m Alex, a Software Developer and RUclips working in the UK. I make videos about software development to help developers with the skills they need to be senior developers. As well as this RUclips Channel, I also write articles on my website (alexhyett.com) as well as write a regular newsletter that contains some thoughts to help aspiring developers.
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#coding #programming #developer
small missed detail, : the bitwise, & and | or whatever, they look if both are set, meaning both are one, not just matching, because if both are 0 for example, & will give zero and not 1
The video is amazing, Thank you, really!.
That is a very good point, I should have mentioned that in the video. Thank you for pointing it out.
For those finding this comment in the future:
IF:
a = 1
b = 1
THEN:
a & b = 1
IF:
a = 0
b = 0
THEN:
a & b = 0
I mean... how can anyone call himself a programmer and then not know the most basic of how computers operate, which literally can be learned in one day?
This is like claiming to be a matematician, but not knowing how addition works.
I will never ever trust any programmer who doesn't know the most basic of his own tool.
I know, and appreciate what you said,
but you know, mistakes happens, and he said he forgot about it, now he does not know about it.
buy anyway, Good luck with your learniing process.
so in the XOR example:
READ_WRITE = 4
WRITE_PERMISSION = 2
EXECUTE_PERMISSION = 1
userPermissions ^= WRITE_PERMISSION
this equals 4 because 6^2 is 110^010, that IS 100, right?
i've thinking... the userPermissions was 7 because of the last operator example, so 111^010 was going to be 5, and the userPermissions "lost" WRITE_PERMISSION but didnt lost execute_permission and read_permission :0 epic
Also, how can the binary number 0011 equals to 6? It's always 3 in decimal...
I've been using the term "bit" when explaining unix permissions ot people for over 25 years, and never understood why. Great video.
I always come back to this video to refresh my terrible memory on bitwise operations. Thank you Alex!
You explained in 8 minutes what my CS professor couldn’t explain in an hour! Great video!
Thank you for this! I've been a game developer for a while and had never had to deal with this concept, but it's been thrown at me with very little explanation in the cybersec course I'm taking. This was very helpful :)
I am glad you found it helpful. They are definitely one of the lesser used bits of programming.
You keep things so simple!! I would love to teach like you do.
Thank you for the kind words! I have never really taught anything before doing this channel. You never know what you can do!
Thank you so much. You helped me with my university exams. Keep going. Well done.
thanks for the awesome explanation and it is good to know when and how to use them.
This was very well-made and informative! You deserve a lot more than 94 subscribers!
Thank you very much, I am glad you liked it.
oh how much he has grown since this comment
This was a really professional video, straight to the point. Thanks for saving my day.
You are welcome. I am glad you found it useful.
Thank you, this helped a ton!
Glad it helped!
Wonderfully explained. Great video
Informative and concise video. Good stuff
Very concise and informative, thank you Alex
Nice! Already learned it but it was still great as a refresher and also a great introduction for newbies to the topic. A shame that the channel is not that big yet
Thanks! I have only started posting regularly at the start of this month so still early days 🤞🏻
Very informative video, thanks and making and sharing it
Thank you Alex, I really learned something with this video. Keep it up
Thanks. Great video
Very very nice video sir, it has helped me out a lot!
That's great! I am glad it helped.
Thank you, this makes things a lot simpler to understand
You’re welcome!
thank you for this because I get it very easy when you explain it
You’re welcome! I am glad I could help.
Great explanation. Thanks
What an awesome video! Super helpful!!
Thank you, I am glad you liked it.
This is so helpful. Thank you!
You're welcome!
very helpful, thank you
Cheers for making this concept so easy to understand.
You're very welcome!
That's excellent content. Good explanation and video editing. +1 subscriber 🎉
Thanks Wesley! Glad to have you here, welcome 👋
great, many thanks from Brazil!
I'm learning DSA atm, and came across a constant time solution for the Power of 2 problem that uses the AND bitwise operator
AMAZING videos, watched both the binary & bitwise operators vids and learned a tonne! Thanks a lot! 😁
Thanks for sharing, I am glad my videos could help!
This reminds me of the days I was learning Z80 machine language programming. Nice video! Are there no bitwise rotate operators, or are they rarely needed in higher-level languages?
good video,very simple, straight to the point and the example of user permission was great and easy to follow. Thanks
Thank you, I am glad I could help!
Excellent explanation, thanks mate!
You're welcome!
Great video Alex and well explained!
I've been using Linux in a while and it's the first time to know the origin behind choosing those exact numbers for files permission, learned a lot!
Thank you, subscribed.
Thank you! Yes I don't think many people realise where those numbers come from. It does seem quite arbitrary at first glance.
couldn't get better explanation!
Sir really , the rwx ex. from linux was amazing , none told us such deeply, thanks for relating bin no with programming & with linux, just amazing
Thank you for the kind words. I am glad my video was helpful!
Thank you so much. I was trying to make sense of some code I came across on GitHub and I had no idea what was going on until I watched this. Didn't think I'd have to deal with bitwise operators in JavaScript haha. Loved the simple explanation and the lighting/graphics.
They are definitely quite confusing if you haven’t seen them before. Even if you have it can take a little while to work out what is actually doing.
Nice vid I would of liked to see the 0 0 table row and some examples uses for the last few operators
Now it makes more sense!
Yeah, this topic was scary to me but you make it seems easy, thanks!
Wow, this video is great, super succinct and explained very clearly.
Thank you I am glad it helped!
nice explanation
I clicked on the like button before strarting the video!
damn man, you should've been my professor in college. now I'm gonna your student on every vid. cheers!
this is gold
Thank you for the kind comment. I am glad it was useful.
thanks Rayan!
Thanks for the video. Not sure I am understanding the point of the 2's compliment. Does that give us the answer of ~5 ? So ~5 is -6?
Programming can be so high level, coming from microprocessors, its a little hard to not have to think about registers and interrupts.
Well, I just learned something cool about UNIX file permissions! I love this, because I use Arch, btw.
That's great! I used Arch a lot when I was younger. Back when I had time to customise everything lol
@@alexhyettdev Lol.
@@alexhyettdev I am 14, so, yeah... XD
@@oglothenerd I remember Arch Linux being really fast. I screwed something up though and couldn’t boot. 🤦🏻♂️
you can use shifts to multiply by 2pow n and there is also >>> operator or
This channel is a gem
Thanks, I am glad you like it!
This'll be helpful for going into raw mode (UNIX).
Im confused, at 4:06 the output is can read, but it looks to me that the result form the bit and should not match so I expected to see 0 ?
I don't think I explained that well in this video. As one of the other comments points out (see pinned) for & operator if both bits are 1 then it will equal 1, if both bits are 0 it will equal zero. If they are both different it will be 0.
So our user permissions are set to 6, which is 110 in binary.
The read permission is 4 which is 100.
If you do 110 & 100 you will get 100, which is why you can do:
if (userPermissions & READ_PERMISSION) == READ_PERMISSION:
What are some common use cases for the last three you mentioned? ~ >
in unity we use these for layer masks. For whatever reason, layers are stored as a series of booleans in a 32 bit (i think) integer... so if we want to mask off layer 7, we have to bit shift 1 over 7 places, 1
That's interesting, thanks for sharing. I have been meaning to try out Unity.
what practical uses do the left and right bit shifts have?
They do have some mathematical uses.
Doing x > 5 is equivalent of dividing x by 2 to the power of 5.
They are also sometimes used for enum definitions which you can see here:
stackoverflow.com/questions/3999922/why-use-the-bitwise-shift-operator-for-values-in-a-c-enum-definition
If anyone has any other uses for them, I would be interested to know too!
@@alexhyettdev thanks!
I use them all the time! Some hardware peripherals will store numerical values in weird places within registers, so to extract them and use them as numbers you need to perform a shift so that each bit is in the right place. Say we had an 8 bit register used by a temperature sensor with the lower three bits being for control and the upper five bits actually representing the temperature. You can extract the temperature by reading the value of the register and doing a left shift by three.
@@JacksonBockus thank you, yes I've come to realise they are widely used in embedded systems to directly access the pins by manipulating the register.
Arduino for example used an extraction layer to turn pins on and off, if you use bit wise it's much faster and parallel
Please tech me this code
Below is part of code that someone wrote for making dot matrix led 8x8 text scrolling
byte bitmap[8][7];
int numZones = sizeof(bitmap) / 8; // One Zone refers to one 8 x 8 Matrix ( Group of 8 columns)
int maxZoneIndex = numZones - 1;
int numCols = numZones * 8;
// Converts row and colum to bitmap bit and turn it off/on
void Plot(int col, int row, bool isOn)
{
int zone = col / 8;
int colBitIndex = x % 8;
byte colBit = 1
Don't stop. There's a long way to go...
Yes it is definitely a long journey!
I am needing to use them because I am making a voxel game.
That’s awesome. I have had “make a game” on my todo list for a long time. One of these days.
@@alexhyettdev Highly recommend Rust with the Bevy engine!
@@alexhyettdev Hi pls my account got banned and i need your help
I discovered using bitwise operators is faster than dividing by 2 for floats
Good to know! Thanks for sharing.
Which language?
@@leonardeuler4 C
@@leonardeuler4any Language
Also multiplying by 2 using the bit shift left operator is faster as well I believe
Teach my class plz
Is your teacher not very good, or just boring? 🤣
This video is a bit loaded for someone who is truly a beginner.
Noted. I will try and do some more videos for true beginners in the future.
@@alexhyettdev Yeah I just find it truly hard to find resources for others on this specific subject. Even 10 years ago.