Let's cover logical AND, OR & NOT.. In case you missed it, here are the previous parts of the series: Python for Beginners, Part 1: How to Download and Install Python Python for Beginners, Part 2: Hello World Exercise Python for Beginners, Part 3: The Turtle Module Python for Beginners, Part 4: Interactive Shell vs. Script Python for Beginners, Part 5: Variables Python for Beginners, Part 6: Strings Python for Beginners, Part 7: Fun Fun Functions Python for Beginners, Part 8: Function Arguments Python for Beginners, Part 9: Loops Python for Beginners, Part 10: Primitive Data Python for Beginners, Part 11: String Slicing Python for Beginners, Part 12: List of Things Python for Beginners, Part 13: Append List-Method Python for Beginners, Part 14: E-1 Circle of Squares Python for Beginners, Part 15: Solution Circle of Squares Python for Beginners, Part 16 - Dictionaries Python for Beginners, Part 17 - Boolean Algebra Jiu-Jitsu Transcript 0:00 So guys what's up this is Qazi from clever 0:01 programmer calm in this video we are 0:04 going to talk about Boolean logical 0:07 operators so in the last video we 0:09 covered the basic jujitsu of Boolean 0:13 algebra kind of like what is the basic 0:17 most fundamental ideas behind Boolean 0:20 algebra and we saw that everything that 0:22 we talked about conversely their true or 0:24 false right so here we have all these 0:28 things converting to true or false 0:30 that's effectively what ends up 0:32 happening at the end so now let's go and 0:37 talk about the operators that I was 0:40 mentioning ok so before I start giving 0:43 you their rules and how they are defined 0:46 in the world of electricity or logic 0:49 gates or programming for that matter I 0:52 want to just give you guys an intuitive 0:54 sense of how it works because that's way 0:57 more important than memorizing these you 1:00 know truth tables for a lot of these 1:02 cases so ATLA so let me get try to give 1:06 you guys an intuition so let's start off 1:09 with and okay we're going to start off 1:13 with this logical operator as you can 1:16 see it's a special word in Python which 1:19 is why it highlights to orange if you 1:21 write and with 2ds it does not highlight 1:23 to orange and let's talk about what it 1:26 does so let's say I did um you know 5 & 1:31 5 it'll give me back a 5 and here it's 1:35 not really making sense 1:36 let's try true and true and let's see 1:42 what it returns it returned true now 1:43 let's try something like true and false 1:45 let's see what that returns that returns 1:48 false so now let me try to give you guys 1:50 an intuition of how it works for and 1:54 let's say there are there two things I 1:57 asked you do you like poison and do you 2:00 like pizza right umm if I asked you that 2:05 question and you could only answer with 2:07 yes or no what would you say 2:12 hopefully you would say false or no 2:15 right and then I would be and if I asked 2:20 you to elaborate then you might say I 2:21 might like pizza but I really don't like 2:24 poison right so the idea behind you not 2:29 liking poison but you liking pizza that 2:33 whole thing when you combine it with an 2:35 end that whole thing becomes false 2:37 because there's one of those things that 2:40 you don't like so you you can't say yes 2:44 to the whole expression that I gave you 2:47 right for and both of the things have to 2:51 be true for you to say yes to it like if 2:54 I asked you do like pizza and ice cream 2:55 you say yeah right but if I tell you 2:59 like jumping off of the cliff or do you 3:01 like jump or do you like doing your math 3:03 homework a lot and you like writing 3:05 essays in that case probably both of the 3:08 things you might not like doing your 3:10 math homework and writing essays and you 3:13 might say no I like doing neither of 3:15 them or for sure you would say false 3:18 right so I can say something like math 3:21 homework let's set it to false meaning 3:26 like you don't like it and let's say 3:29 long essays is equal to false and now 3:34 let's combine the two let's say math 3:36 homework and long essays you get back 3:41 false right math homework is really 3:46 false and long essays or false so false 3:48 and false gives you a false now let's 3:51 try pizza and let's say we like it for 3:54 my friend Danielle he loves pizza so if 3:56 you're watching this video that's who I 3:59 was thinking of when I came up with this 4:00 example let's do ice cream and let's set 4:03 that to true meaning we like both of 4:05 them and let's do pizza and ice cream 4:08 right and you get back true so even 4:12 thinking about it logically 4:13 whenever you combine something with an 4:16 end both of those things are now 4:17 combined so when you're answering you're 4:19 answering for both of them even in real 4:21 life both of those things have to be 4:23 true John 4:25 go throw out your garbage and then you 4:28 get to play right 4:30 so in that case both of those things 4:34 happen to be true if you throw out the 4:39 garbage you know then you kind of get to 4:41 play it's a little bit of a contrived 4:42 example there's more of an if-then 4:44 statement rather than an end okay how 4:48 about this even better 4:50 Johnny throw out your garbage and do 4:52 your homework and then you get to play 4:54 okay in that case the only way Johnny 4:57 will get to play his game is if he has 5:00 thrown out the garbage and done his 5:02 homework much better now I can now I can 5:06 sleep better all right that's the 5:09 breakdown for end so now let me just 5:12 give you some problems and throw it at 5:14 your face okay false and false quickly 5:17 what do you think is going to be you 5:19 should have said false false and true 5:23 remember one of them is false both of 5:25 them end up being false because we can 5:29 imagine that this is poison and then 5:31 this is pizza and you can't say true to 5:34 both of them because there's one of them 5:36 that you don't like for it to be true 5:39 both of them have to be true what if I 5:42 gave you true and false what if I gave 5:45 you true and true what do you think that 5:47 would be okay hopefully you're trying to 5:49 get a little you're starting to get a 5:51 little bit of sense of this why this 5:53 will be important later on is once we 5:55 get to the conditionals of control flow 5:56 section which we should be getting to in 5:58 the next video and there we're going to 6:01 be talking about how you can combine an 6:03 if statement use an end to check two 6:06 conditions and then the block of code 6:08 runs so if Johnny homework and pizza or 6:15 and I don't know throw out garbage then 6:23 this code here runs okay obviously I'm 6:29 going to hit syntax errors right now 6:30 because I haven't defined Johnny 6:31 homework I haven't defined throw out 6:33 garbage and you can't write stuff 6:35 separated by spaces and I don't know who 6:37 rights capital variables only if it's 6:41 constants but we'll get to that later 6:42 all right so now let's go to the or side 6:48 of things what if we combine two things 6:49 with an or if I asked you do you like 6:53 pizza okay for sanity check assume you 6:58 like pizza even if you don't okay so 7:01 just to play along just imagine you like 7:03 pizza so if I ask you do you like pizza 7:06 or doing homework if you had to answer 7:12 that with the true or false what would 7:14 you say if you like pizza or doing math 7:18 homework if you could only enter the 7:20 true or false or yes or no you should 7:23 say yes or you should say true because 7:27 there's one of those things that you 7:29 like and I asked you or they're not 7:31 connected with each other right A or B 7:34 so let's now get and let me show you 7:38 guys this in code if I do false or true 7:40 check out what you get back you get back 7:42 a true statement right if I do true or 7:47 false I get back a true statement and if 7:51 I replace this with something that we 7:53 understand better let's say we don't 7:55 like poison poison is equal to false and 7:58 let's say we do like pizza and we 8:02 already have pizzas true but I'm just 8:04 going to do that it can and now let's 8:06 write this statement over here using 8:09 pizza and poison sorry 8:14 pizza or poison OH 8:19 I misspelled poison but in one of my 8:23 older videos I had it there so don't 8:25 worry about why it figured out what 8:27 poison was but um 8:29 yeah let's just let's just use this 8:32 poison variable that we wrote here so 8:34 you can see that we get back a statement 8:36 that's true because one of the things is 8:39 true and in this case that's pizza so 8:42 for an or statement to be true only one 8:44 of the things have to be true right if I 8:46 asked you do you like ice cream and 8:51 or pizza you would say true if you could 8:54 only answer that with one thing just 8:57 like if you know again we take Johnny or 9:02 our son Bob and we go Bob either if you 9:08 do your homework 9:09 or you throw out the garbage then you 9:11 get to play so he just goes oh sweet I'm 9:14 just gonna throw out the garbage so this 9:16 way he doesn't have to worry about doing 9:18 homework he decides to only do one of 9:20 the tasks and then he can play the game 9:22 but what if he went and tried to be 9:25 extra nice and threw out the garbage and 9:27 then when it did his homework but he 9:30 still would you know us being his dad or 9:34 mom still allow him to play of course he 9:37 did both of the things great that's 9:38 extra bonus but for him to qualify as a 9:42 player or like go play his games 9:45 he really needs only one thing that's 9:47 what the order does in our real life and 9:49 so that's what it does in programming as 9:53 well so now let's just let me just throw 9:56 some examples at your face and you try 9:58 to figure it out 9:59 true or false what do you think I'm 10:01 going to get quickly I'm going to get 10:03 back a true only one out one of them has 10:05 to be true what if I did true or true 10:06 what am I going to get back true 10:09 obviously what if I do true or or sorry 10:13 let's do false or false - false 10:16 statements you like poison or homework 10:21 you're gonna say no you know none of 10:27 them there you go so that's a little bit 10:31 of a breakdown of or and if I wanted to 10:34 break down not for you not is very 10:36 simple not is just something that 10:40 doesn't happen okay so it's it's just 10:43 the negation of something so if I said 10:45 not true what do you think I'd get back 10:46 I get back false if I did not false what 10:50 would I get back true it's just a 10:53 negation so if I do something like not 10:55 true or false what do you think I'm 10:59 going to get back what is this 11:01 expression going to evaluate to true 11:04 or Falls remember for something to be 11:07 true in the or but combined with the 11:09 oral boolean logical operator only one 11:12 of the statements has to be true so here 11:14 we do have a true so true or false 11:16 evaluates to a true and then right this 11:20 pretty much becomes true and then 11:22 calling not untrue gives us false so now 11:26 let's just run it okay and as you can 11:29 see we get back false so what I'm going 11:32 to do for you guys on clever programmer 11:34 comm is if you guys go to submit your 11:37 exercises here what I'm going to do is 11:40 I'll have or sorry if you go to do the 11:42 watch the video course on my website I 11:44 will have exercises here for you where 11:47 you can kind of drill and kill how true 11:49 and false and the stuff Boolean 11:51 operators work that's going to be very 11:53 very useful for you guys so then when 11:57 you're writing your if-then statements 11:59 you'll understand what you're doing okay 12:02 but this is kind of you know we just 12:04 need a basic understanding of it some 12:07 places go really crazy in depth into it 12:10 like creating things like not true or 12:12 false or true you know just just 12:18 combining it and making it into it like 12:23 these can be good exercises for you to 12:25 figure out but realistically when you're 12:27 writing code you're not going to be 12:28 doing stuff like this so if you can 12:30 figure this out in your head great but 12:33 um you know like you're not writing code 12:36 like this most of the time so I wouldn't 12:38 want to worry about it too much but if 12:40 you want to go ahead and give yourself 12:41 some crazy exercises like this to do or 12:44 come to my website where I'll have some 12:46 exercises for you guys to do that would 12:47 be great and before I conclude this 12:51 video let's go back to here I have put 12:55 together a truth table for you guys or 12:59 rather it's on Wikimedia @ org so I 13:04 didn't put this together but I have an 13:06 image I'll link you guys the image and 13:07 you can see how the truth tables work so 13:12 in the a column we have some statement 13:15 imagine it being P 13:17 it's a-- right we have that statement 13:20 and be say some other statement so we 13:23 don't really know what these statements 13:25 are for now but you can imagine them to 13:27 be whatever you want so let's say we 13:29 have some statement and some statement B 13:31 if a is false and B is false then a and 13:35 B you get back false right remember and 13:40 so if you have again a being poison and 13:45 B being homework poison and homework you 13:50 get back false you like neither of them 13:52 and if we have a or B since both of them 13:55 are false it's still false and not a is 13:58 just the opposite of that you get back 14:02 true and same thing over here we have 14:06 false and true false and true gives you 14:10 back a false false and true you only 14:14 need one thing to be true in or 14:15 statements you get back a true and then 14:17 not a which is saying you know opposite 14:21 of a since a was false you get back a 14:24 true ok so one thing I need you want you 14:28 to notice about and operator and or 14:32 operators if you look down the column of 14:34 the end operator you'll only see one 14:36 true case and the reason and the only 14:40 reason why it's true is because both of 14:43 the statements are true okay that's the 14:46 key thing to remember both of the things 14:49 are true and if you go and look in the 14:50 or column you'll see the or being false 14:55 only in one case and the only case is 14:57 false is when both of the things are 14:58 false okay so notice the key distinction 15:01 between the two okay 15:04 that's kind of all you have to know for 15:06 a Boolean stuff and I'm not going to go 15:08 into the next video with the really long 15:10 nested Boolean statements it's kind of 15:12 useless we don't really think that way 15:14 anyways and we're gonna get into 15:18 conditionals and control flow so I will 15:20 see you guys there

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Python for Beginners, Part 18: Logical AND, OR, NOT

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