Python Jumpstart by Building 10 Apps Transcripts
Chapter: App 2: Guess that number game
Lecture: Getting started with Guess That Number Game

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0:00 So let's jump into PyCharm and start building this game.
0:03 Remember, our convention is that we are going to
0:05 start out with the main thing we run called program,
0:08 so our new Python file called program.py
0:11 and our app, as the very first thing it had at the top a header
0:15 so remember we'll do print
0:17 and we had a bunch of dashes here.
0:18 Now in PyCharm, if you want to duplicate a line
0:22 or a selection or a set of lines,
0:23 you can hit command D in OS X or in Windows or Linux control D.
0:28 So I will hit command D a few times,
0:30 it's a little bit of a shortcut.
0:31 And then it said guess that number game, something like that,
0:36 let's do some centering, and finally let's do a print,
0:39 just to leave some space there at the end.
0:42 Before we go any further, let's just run this really quick
0:44 to make sure everything is working,
0:46 again, there is no run configuration up here
0:48 because this is a new project,
0:49 so we'll right click and say run,
0:50 and then all right, a little header is working fine.
0:54 Now, the next thing we need to do
0:55 is come up with that random number
0:58 and the number the computer guesses
1:00 so I will create a variable called the number
1:02 and now, somehow we need to come up
1:05 with this random number
1:07 and one of the great things about Python is
1:08 it comes with all of these modules and libraries that we can use
1:12 one of them is called the random library, or the random module
1:15 Now, PyCharm is not happy,
1:18 because we need to actually tell Python
1:20 we intend to use a module that is not what is called the built in
1:25 this is like an extra part of Python
1:27 so we need to explicitly state I'd like to use this part of Python
1:30 this works identical to whether it's something in Python
1:33 with the standard Python implementation,
1:35 or something external, like some other library that you've gotten.
1:40 So we are going to say import,
1:41 and we just say random,
1:43 and then we'll say random.
1:44 now we have a bunch of options, a little warning went away,
1:47 the one we are interested in is randint
1:49 we'll come over here and call randint
1:52 and if we hover here for a moment or pause for a moment,
1:55 it will say it takes two parameters a and b.
1:58 Now, so I would guess that those are numbers,
2:00 and I'm sure you would as well,
2:02 and that they somehow specify the lower and upper bound
2:05 that we are suppose to work with here
2:06 but is this including those n points,
2:10 somehow between these n points,
2:12 and we can check the docs,
2:13 but it turns out that this actually includes both n points
2:16 so what we want is 0 to 100.
2:18 Let me show you something that PyCharm can do for us
2:21 that really is pretty amazing
2:23 and one of the things I really like,
2:25 imagine let's roll this back for a minute,
2:27 imagine that we don't have this import going on,
2:29 and we don't have this line,
2:31 so here we are again and we want to say
2:33 just like before the number is equal to random.
2:36 Now PyCharm has a little red light bulb
2:39 you can see there and it says,
2:40 Hey, this is not right, but I am pretty sure I can fix it for you, automatically.
2:46 So if I hit alt enter, it will come up with the list of options to fix it,
2:50 so I could actually just hit enter and it will say
2:53 we are going to import random
2:54 and there is a couple of ways we could do it
2:56 but this top one is what we had done before,
2:59 so I can just hit that,
3:00 and you could see right at the top it added import, random,
3:03 now I can type randint and off we go.
3:05 So, a lot of times when you see an error like this,
3:08 one of these red squiggles and this little light bulb in PyChram
3:12 that means that there is some kind of auto fix
3:14 it's going to propose for you and it is probably worth checking out.
3:19 Ok, excellent, so we have our number guessed,
3:22 our number between 0 and 100 inclusive,
3:25 now the next thing to do is get some input from the user
3:27 and we are going to just tell the user
3:28 hey, enter a number between 0 and 100
3:31 so I'll call this guess, and this is going to come back as text
3:34 so I'll be very explicit and say guess text
3:35 so we'll say input, just like before, guess a number
3:43 so guess a number between 0 and 100
3:44 and we'll just let the cursor stop right there, and we'll wait for that.
3:48 Conceptually, the next thing that we are going to do
3:50 is we want to compare the number against the guess text.
3:53 Now, Python is not a very forgiving
3:55 about a quality between numbers and strings,
4:00 these don't really have anything to do with each other,
4:02 so if we tried to just say print, put whether the number
4:05 let's say less than the guess text,
4:07 if I try to run this you will see it'll actually crash,
4:09 so if I put in 42, and it says you cannot sort between
4:15 or compare the order of integers and strings together.
4:19 You can ask whether they are equal,
4:21 they will never be equal, but you could ask that question,
4:23 but you cannot do the type of comparisons that we need for this test
4:27 So the next thing we need to do is
4:29 actually take this guess text and convert it into an integer
4:32 and we'll call that integer the guess
4:34 so this is super easy, the int class is just built in
4:37 and we can call it initializer like this
4:41 we can pass it some text
4:43 and then what is going to come out is actually a guess
4:45 so we could say really quickly print the guess text
4:48 and you can actually ask for the type of these
4:50 so let's print those two out
4:51 and here we'll print the guess and the type of the guess
4:55 so if we run this two, if I enter 42,
4:58 it means the first line where was guess text is actually a string,
5:02 str is the string class in Python
5:04 we've actually converted successfully to 42
5:06 it looks the same when you print it out
5:09 but it's definitely not the same type in memory.
5:13 All right, the next thing we need to do
5:14 is write some conditional statements with if and else statements
5:18 and some comparisons and so on
5:20 in order to determine whether we have won the game
5:23 the guess was too high, too low, that sort of thing
5:25 this is one of our core concepts from this application
5:28 so let's go dig into that.