Learn Python For Beginners 2020 | Tutorial Part #2

if that is the question hi today we're going to be looking at if-else conditional statements in   python for lesson two in the series of getting started with python so let's get straight to it hi guys i'm david and today we're doing our second lesson in our course on how to   get started in python and today we're going to be looking at if statements with strings   and integers so i guess the best idea is to get to our computer and get started with it

Second Lesson

right this is the second lesson in the course if you haven't done the first lesson on getting   started with python i suggest you go to the card above and click on that to do that first   today we're going to be looking at if statements so i've started a new folder and created a main.py   just like in the first lesson and i guess we should get started right as in the first lesson   

we're going to start with integers integers as you know if you did the first lesson are a variable   which is a number a number which can be any number so we're going to start with i equals zero so what   we actually want to do is ask python to print out a statement on the screen if i equals zero or   or if i equals one so let's get to that the good thing about python is it's pretty plain english   so let's go if i equals equals zero and then you press the double dot to end the statement now what   

you're actually going to do now is press enter and inside the visual studio they will automatically   indent it everything that's indented will be part of this if statement so we're going to write print we're going to do double quotes here and we're going to write i is equal to zero then we're going   

to go down to a line and we're going to press backspace and write else now else means that if i   if i is not equal to zero we're going to print something else out so we're going to press enter  

 again and that's going to indent the text print i is not equal to zero so then we're going to save   that and we're going to run the script so what's happening here is your python scripts checking   to see if i is equal to zero if it is will print out like in the last lessons so let's go python  

 main dot p y and as you can see i is equal to zero because we said i up here now if we work it out as   one then press save and rerun it it will say i is not equal to zero so the if statement is 

  working perfectly well okay so let's clear that and move on to something a bit more complicated so   what happens if i is more than zero so it could be any number that's above zero okay so let's go i i

   is greater than zero so i is greater than zero let's save that and see if that works i is greater than zero of course it is because it's one now what if we set this to zero   and run again i is not greater than zero because it is agile equal to zero so that works as well  

 what about if i is equal to three no i is greater than three so for this work  

 i is not greater than three so we're gonna offset i to four and that's working absolutely perfectly wonderful right it's because i is four so it is greater than   

three it should say three here but anyway you know what i mean right okay fantastic so okay so   now you've done your first if statement i know it was simple but that's the great thing about  

 python everything's written in very much plain english so it's understandable and easy to code   

let's go on to something a little more complex and add an else if statement so that's going   to give us another condition to our conditional statement so let's give that a go okay so we're   back here i've done and then we can add an else f now to do an else if we have to type l sif i equals equals four and then we're going to go here and we're going to do a print statement  

 i is equal to four so now what we have is an if statement saying that we have i is equal to three   if it's not it may be equal to four and if it's not it will print this so let's give this a go there you go i is equal to 4 which is great that's wonderful you've now done your first 

  conditional statement 

in python so let's have a look at maybe adding some strings instead   of an integer okay what happens if we decide to make this into a string so this is a just string   so if we go here and then we type this and then run it we're going to clear the   terminal down here and run it see what happens you see it's not equal to zero which is perfectly  

 great because it's a string now so how would we do it if we wanted to return a string that only   inc contained the word this in it okay the best way to do this is to go back to our if statement   here and modify it i'm going to comment all this out now to comment out all you have to do is do   this like this highlight all and then do control and that will   

that will comment out all of the team now comments you may not have seen before comments will put a   hashtag in front of the statement which means the computer will see them but will not run them   so it's very useful if you're adding tank for another developer or reminder to yourself of   

what an actual function does so right here we could write this is a function for if string okay now we can get on and we will know next time here that we come here   anything below this line will work with an f string right okay okay to do this what we're  

 going to do is we're going to create another string which is going to be the found string   okay found string is going to be the words that we're going to be searching for this is okay so if found in i we're going to type print i found do and then if not we're going to do else and then else we'll print not found okay so the idea is is if we find the text this is inside the i 

  string we'll type out i found you and if not we'll type not found okay so let's give it a go i found you so as expected python actually found inside the string   the text that we were looking for and then printed out the statement that we wanted   

okay now we've done the simple strings maybe we should look at some arrays   an array is a list of strings or integers all stocked into one variable so i guess  

 that's the next idea okay let's have a look at this then all right okay so array could be   

u equals and then we go over here in between a square bracket so we're going to write apple and then here and then maybe we should write windows and maybe what about doors okay maybe i should spill that quick okay so inside   

this one array we have several values okay so how would we go about printing out these   photos let's have a look at printing them to the console if we go print   you this is what you get back i'm going to comment this out so we don't get the old comments here   we're going to save okay let's print u to see what happens okay as you can see we have  

 the full array 

of all of the values in uh printed out now what if i wanted just to print out apples   so anything about arrays is that actually they all start with zero so let's go and write u  

 squared brackets zero

and that will bring up our first value which would be apple if we   wanted pair it would be one if we wanted windows it would be two try windows and go windows okay   wonderful so now we have a look to the slide uh now i've looked a little bit into arrays maybe   

we'd do an if statement with an array so how would we go about doing an if statement for an array so   we're going to do a found straight versus found string again here and we're going to write apple much like this string above we're going to try if found in you and i'm going to print out i found an apple and then we're going to go down to next slide and right else   all right statement which is going to be simply nothing here okay cool right now let's have a look see whether that works   

we're gonna go brian and i found an apple fantastic that's brilliant so it's   actually gone through our array and found an apple inside our array that's wonderful   okay we've had a bit of a look into if statements and how they work we even went into slightly   

deeper into an array and we also looked at adding comments to our script to actually getting   into python and how it works I hope you enjoyed this lesson it's part of a series that I'm going 

  to be doing out every day of the week so I'll see you tomorrow if you like the video thanks   for liking it and please don't forget to subscribe for the next videos have a great day cheers bye