Learn Python in Under 30 Minutes

Key Takeaways

what's up YouTube if you're interested in learning python but you don't have a lot of time this video is for you we're going to cover the commands you absolutely need to know to start as a beginner in Python and we're going to do it in about 20 minutes so we're going to take a word from our sponsor really quick and then we're going to jump right in as always if you like the video please do consider subscribing to the channel shout out to our sponsor for this video sneak who is running yet another fetch the flag CTF this time they're running it with John Hammond and he's got this awesome little bitemoji from sneak sneak how do I get one of these this is really cool anyway this petch the flag CTF is going to be a 24-hour event and it's going to start on October 27th at 9 a.m. eastern time make sure you mark your calendars it's 100% free and it's made by John Hammond so you know it's going to be quality so there's going to be a handful of challenges here there are 30 plus challenges it's going to have web binary exploitation and so much more and really this is for beginners all the way up to advance you can be at any skill level to participate in this and they've got really cool prizes too so all the top three winning teams are going to get a Nintendo switch and of course bragging rights now if you're interested in the event registration is super simple you just scroll down to this page at the link that I'm going to provide you which by the way is snak.io and look how easy that was you're registered so again if you're interested in registering for this go ahead and go to sneakcollector I prefer Visual Studio code again just type in Visual Studio code download I'll link this in the description below you just come here download it click next next next install run it and you are ready to run python lastly if you like this video we do have a full course on YouTube completely free it's a three-hour course and expands upon everything that you see so if you want to learn more after this video and go above and beyond with some challenges and other things please do consider checking that out I'll also link that in the description below without way let's go ahead and get started with python okay so first up our strings now we typically run our first program in Python with the print statement so we come in here and we say print hello world now hello world here is a string you can tell that because it's in quotations and really what's important is that strings are typically human readable format they're not made for a computer so when we have our print statement here we can run this with quotes we can run this with single quotes we can also run this with triple quotes if we wanted to have this cross different lines or multiple lines we can come in here and do what's called concatenation with strings we can say this string is put a nice little space in here do a plus sign and then add another string and say awesome we can print out a new line by doing a back sln we can also say test that new line out so when we run this code here let's take a look at what we actually get here you can see that we have Hello World okay that's corresponding here hello world this string runs multiple lines perfect we printed out this string is awesome looks great we printed out a new line which should just be a blank line which we get here and then we say hey test that new line out and we printed yet another string so other things to note in here is we have what are called comments we have this comment here which typically they are with a pound symbol or a hashtag and we come through and we can comment anywhere we want these comments are not read by by code so we can use comments throughout our code in order to just make notes for us which makes us a better developer so we like to leave these comments in here where possible and just so that somebody can come along and actually read these comments if they're working on your code that you wrote next up is math python has the capability of doing math and here all I'm going to do is put together a bunch of print statements that are doing math functions here so for example we can do addition all we have is a plus sign subtraction multiplication division we can also do pemos so please excuse my dear Aunt Sally or whatever you might have learned in class and we can do that and it will automatically just pick it up and do the pem Dos for you we'll see that we can do exponent so if we want to take 50 to the second power all we got to do is use two asteris here we can do what is called a modulo or modulo I don't know how you say it but a percentage sign here we get a leftover so if we do 50 divided 6 we know we get 48 we should have a remainder of two so this will actually print out two we can do division with decimals here with just a straight division or a forward slash and then we can come here and do a no remainder so all we would get would be eight here and not have a remainder nor any decimals so let's go ahead and save this and print this out and take a look at what that looks like and you can see exactly here we've got the addition the subtraction we've got the multiplication the division here we can see we do have a decimal point here and 50 / 50 is 1 we come through and look at pemos which will automatically calculate and actually resolves to 50 50 * 50 is 2500 we've got 50 ID by six what's remaining is two here we've got division with decimals which is 8.33 3 3 3 33 forever okay and then we have no remainder which would just be eight here next up we have variables so for example we can set a variable here of quote and we can tell quote to equal All is fair and Love and War and this is a straight string so all we're doing is storing this string into this variable quote and here we can come back and print quote so if we save this and run it we should be able to print out All is fair and Love and War next up we have what are called Methods now methods are like mini programs they're basically functions that are automatically built in we haven't talked about functions yet so don't worry too much about it but just know that methods are built into Python and you can actually learn these so for example if I wanted to print out that quote that we took and I wanted to make that in uppercase I could do a uper and that would make it uppercase I could do lower case title case I can even count the amount of characters that are in the quote all because we're using these builtin functions in Python so if we save this and run it you'll see that we have uppercase here we've got lowercase here we've got title case which is just capitalizing everything it's not great here but it's capitalizing every first letter and then we have the count of all of the characters inside that does include Spaces by by the way but if you counted all these characters it would total up to 28 we've talked about strings now let's look at numbers so I've got three variables here let's say that my name is a variable and that is a string I've got an age variable here which is an integer and I've got a GPA which is what's called a float the best way to think about a float is a float has a decimal an integer does not so if I want to come in here and I want to print out my age I can say hey I want to print the integer for example of my age and will give me just 33 if I came in here and printed out the integer of 30.1 I'm going to actually get 30 it's going to round down no matter what if I print out the integer of 30.9 it's also going to round down and give me 30 let's take a quick look at that so you can see here that we printed out the age which is 33 that's correct and we get 30 and 30 here on both of these so just know that if you take an integer it will not round up it will always round down now there are a few things that we can do with these variables and putting them into Strings for example so if I want to say my name is Heath and I am x amount of years old I can do that I could say my name is name and this is just doing concatenation and I am however many years old the thing is here I am putting this age to a string because you cannot concatenate a string and an integer so if I were to take this away for example I would get a glaring air here let's see if I just take it away if it yells at me and I try to save this it's going to say hey you can't you can't do that because you can only concatenate strings not integers so if we come back in here and we go back and save this and now run this we should be good here you could see my name is Heath and I am 33 years old let's say that I had a birthday I could just easily say age plus equals 1 and that will print out my new age I can also say that birthday means that I get an year increase so if I say birthday is equal to 1 and then I say age is Plus or equal to birthday all I'm saying is age is Plus or equal to one so this variable here is storing an integer that integer is then being increased so I've got my integer of age and then I'm increasing that by an integer and I'm printing that out here which is now giving me 35 moving on let's talk about functions now I mentioned earlier functions are just like little programs a method is a function here we can actually make our own function so let's say that I wanted to create a function that was called who am I well I can come in here and first I'm just going to print out and say here's an example of a function and what we're going to do is make this function so a function starts with DF and we're going to Define that function we're going to call this who am I here and then we're going to say hey my name this is a variable is equal to Heath my age is equal to 30 and I'm going to print out that same thing my name is Heath and I am 30 years old now one thing to note two things to note really one we have spacing here this is very important when it comes to python you have to have indentation so this is four spaces added here or it's a tab depending so if you came in here and added four spaces perfectly fine if you did a tab that's perfectly fine as well if you see now that I've saved this I'm getting an error because I have a mixture of tabs and spaces so you have to be consistent you can't just do four spaces if you're going to do a tab so if I come in here and I fix that that should fix everything else for me and then I should be good to go so I'm going to save this and what's going to happen here is I'm going to print this out all I'm going to do is call this function and I'm going to run that and it's going to say my name is Heath and I 30 years old well what's Happening Here is I have this age variable right and I'm calling that and I am 30 but didn't I have an age variable up here I did so what we're seeing here is within this function we have the variable of age and name these are actually local variables meaning meaning that they are not Global when you set a variable here outside of a function we are having a global variable so if I were to come in here now and just print age you would actually see that I have a variable that is 35 because that's the last time we used it we incremented it and made it 35 so know your differences if it's inside of a function and it's a variable that is a local variable if it's outside of a function like this here that is actually a global variable and holds consistent until you change it okay so I've added a bunch of functions in here so let's take a function for example where we just add 100 to a number so we have this parameter here of num and all we're going to say is print num plus 100 so when we provide that value this should then spit out 200 for example we'll take 100 + 100 or if we put 200 in here it would be 200 + 100 which would spit out 300 we'll take a look at this in just a second we could have multiple parameters as well so if we wanted to add something we could Say Hey I want to do a function of ADD and we'll provide it X and Y and when we do that we'll print out x + y here if we wanted to add 7 + 7 we would get 14 do the same thing with multiplication okay 7 * 7 perfect and we could do a square root as well we know square root is an exponent to the half power if we wanted to do a square root here and so if we wanted to square root 64 for example we should in theory get 8 one last thing I did here was I made a function for a new line earlier we printed a line out with a back sln well what if we just made a function called new line didn't give it any parameters all it did was just print this new line we could do that as well so anytime we type new line it should put a new line in for us moving forward so if I run this save it and run it we should get a bunch of new info out here so you can see hey I've got my 200 here which was 100 plus 100 I've got 14 which is 7 + 7 49 which is 7 * 7 and we've got 8 which is theare < TK of 64 then you see this nice space here for a new line next up are what are called Boolean Expressions Boolean Expressions just basically mean true or false so we could set different variables to true or false and we can say things like Boolean one for example we just say that's a variable we can set that equal to True note that this is capitalized okay well we could also say well 3 * 3 is equal to 9 okay we have the double equals meaning that we're saying this evaluates to this okay well is 3 * 3 9 it sure is so this will evaluate to true we could also just say false or we could say 3 * 3 does not equal 9 and that is also false because it does equal 9 so we can come in here and say print these out and you'll get true true false false we can also Al say what is the type of the Boolean we'll take a look at that and then we can make a Boolean 5 here where we put this in quotations and we're going to do a type on that as well what do you think this is going to be it's not going to be a Boolean it's going to be a string okay so if we print this out you can see here that we return these Boolean Expressions true true false false that is exactly how it valuates and then we also have this class of Boolean here because that's the type we're printing out or if we printed this out here that's actually a string so know the difference between quotations for a string and a true statement here this is why having an IDE is nice because you can see the color differences very easily we also have relational operators that can evaluate to Boolean Expressions too so we could say for example we have a variable called greater than seven is greater than five okay that is true five is less than seven that is true okay greater than or equal to that is true here less than or equal to as well as well so I just want you to know that these operators exist and they can evaluate to true or false we can also have what are called and or statements we can also have not statements so we could say hey seven is greater than five and five is less than seven that is true 7 is greater than five and five is greater than seven that is false also we could say seven is greater than five or five is less than seven and only one of those has to be true to be true or we could say 7 is greater than 5 or 5 is greater than seven and again that is true because only one of these have to be true so with and both of these statements have to be true with or only one has to be true to evaluate to true and we can also say not true so if we said this is not true all that would mean is that this is false and you might think why do I even care about all this well because it comes down to what are called conditional statements let's say for example now we have a function of drink and drink is defined by how much money you have if you have enough money you can buy a drink if you don't have enough money you can't buy a drink so if the amount of money that you enter in is greater than or equal to two then guess what you can return that hey you've got a drink otherwise if not no drink for you so what is it saying if true return this else meaning if false we're going to go ahead and just return no drink for you so if we print out drink of three for example that means we have enough money and that should EV Val way to True versus a drink of one which will give us no drink for you okay let's look at another one with alcohol as a function let's say that you're trying to buy an alcoholic beverage well for alcoholic beverages at least in the United States you have to have money right but you also have to be a certain age in the United States that is 21 so there are possibilities that we can have enough money but not be old enough or be old enough and not have enough money so we need to write out a function that would think about all of those things logically so we're going going to say hey let's define alcohol with age and money and if our age is greater than or equal to 21 and our money is greater than equal to five then guess what we're going to be able to get a drink because we've got enough money if we're old enough but we don't have enough money it's going to say come back with more money if we are not old enough and we have enough money it's going to say nice try kid else if we are too poor and Too Young it's going to tell us you are too poor and Too Young so what you're seeing here are if statements followed by else if if here previously we just had an else statement in here so we said if else here we're going to say if else if else if else depending on how many conditions we have and then we could just come in and print this out and if we do that all we have to do is look at it you could see that we have one situation for each of these so we return hey we're getting a drink come back with more money nice try kid and you're too poor and Too Young depending on the situation here next up our list Now list are data structures they're changeable we can reorder them and I like to think of lists as having brackets that's a good way to think about it you'll see why so with our list here let's say that I've got movies and I've got a bunch of movies that I like and here are four movies that I like on my list well within this list we can do things to return certain data if I print a one of movies for example within brackets what we're going to do is return the second item in the list this is what's called an index so in the index we actually start with a zero not a one so if I want to return the first item I'm actually going to return with a zero this is item one this is item two this is item three now we can also slice this and we can say I want to return the first number given until the last number given right here or the last item before the number given so if I want to return item one and item three well this is only going to return item one and two this will return item one two and three this one will return item one and everything from this number to the end of the list okay this is going to return everything before item one everything before item two negative 1 will grab the last item so this is speed running through this a little bit I'm going to just show you real quick let me save this in print and we'll take a look at it again but if we come back and look at these you could see that we're coming through and we are pulling down this data so hey if I want to pull the second item in the list with one that's going to return the hangover the first item in the list is When Harry Met Sally that returns perfectly if I want to return one to two I'm actually going to put one to three so I should get the hangover in The Perks of Being a Wallflower if I wanted to turn one to three I actually need to put 1 to four or I can come in here and just say one to blank and don't put anything that will do the same exact output if I wanted to return everything before item one which would just just be item zero that would return just like that everything before item two would be zero and one so we' get that and if I want to grab just the last item in the list just do a negative one which is the Exorcist there we can also apply methods to this like hey what is the length of this list movies there are four in there okay if we want to append a movie to this we can't so let's say we want to pend jaws and we put that to the end of the list well Jaws is now put here on theend of our list if we print out this list if we wanted to put a movie in a specific place for example hustle we want to put it third on the list we'd actually put it on two and we say Okay hustle is here print movies you can see hustle is now in slot two where 0 one two we can also remove an item from the list if we wanted to remove the last item we could just do a pop and pop would remove Jaws we wanted to remove the first item we could do a zero for example and then that would remove When Harry Met at Sally so just know that you have the capability of adding appending removing and using methods on these list as well and then you have different ways to slice these lists in order to call them should you want to now let's take a look at why lists are important okay next up is looping and this brings list right back into play so we have two different types of Loops that we want to concern ourselves with right now we have a for Loop and a wall Loop a for Loop is the start to finish of an iterate so let's say we have a list here of vegetables and in our list of vegetables we have cucumber spinach and cabbage let's say we want to print out every single item in this list how are we going to do that well we could technically print the list right we could say print vegetables but that would print it out kind of like you see here let's say we want to print them out one by one we could do that we could say for x and x could be whatever you want you could say I item veggie and vegetables whatever you want to call it doesn't matter in vegetables now this is what we are calling here we're going to print X so for every item in this list from start to finish we're going to print that item out that is a for Loop for blank in vegetables whatever we want to call it we're going to iterate through that we also have what is called a wall Loop and this is where the Boolean statements become important let's say that we have I is equal to one well wall Loops execute as long as they are true so if one is less than 10 it's going to print out one and then it's going to come back and say 1 plus or equals 1 so when it goes back through the loop again it's going to print 2 is less than 10 so it's going to print out two go through the whole process again so as long as this is true it's going to work so while I is less than 10 up until we get to 10 right once it's 10 10 is not less than 10 so it's not going to print 10 we should expect to see this print out 1 through n so let's save this and we'll print this out and we'll see okay 1 2 2 3 4 5 6 7 8 9 and we have cucumber spinach and cabbage here because we Loop through this list here okay lastly I want to talk about importing modules importing is important so there are modules built into python that we can utilize for example we have this CIS module this is system functions and parameters we'll take a look at that here in just a second and also we've got this module called date time so instead of just saying import date time we can say from date time import date time as DT and what we're doing here is we're actually importing this with an alias so now we can utilize these modules for example if I want to print out the version of python that we're using we could say print sis. verion or if we want to print out the date time that it currently is we could say print DT because we gave it an alias and do a now because now is a method that we can use so we're going to come in here and just save this and we'll run this again and you can see that hey I am on Python 3.1.2 and today's date is 10:10 2023 yeah we've reached the end of this very short video and we've covered a lot of topics in a very short period of time if you're interested in learning more about python we do have a video full course three-hour video on this YouTube channel I'll link it in the description below it's called python for beginners it covers a lot of what you just learned in deeper explanation there's more topics there are challenges all kinds of fun stuff in there that will get you ready to Learn Python and to excel to the next level so hopefully you found this video valuable if you did please do consider subscribing to the channel outside of that my name is Heath Adams AKA The Cyber mentor and I do thank you for joining me peace out