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Hello, I think we have learned enough

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that it's time for a little bit of a mini project, something

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fun. And so we're going to create our first little program.

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Now, I'm going to show you exactly how I'm going to create a program,

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and if you want to, you can download the source code, and

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you can modify it to your hearts content,

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or you can try to make one on your own as well.

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Now I'm going to show you how you can create a Python program,

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and then run it inside of your command line program.

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So effectively we will be creating a brand new program.

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So let's create a new file here.

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I'm just using VS Code.

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It's a regular text editor.

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There's nothing fancy about it.

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I'm going to assign the file type as Python.

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And let's go ahead and save this to my Desktop, because I'll

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be able to find that. 'program.py',

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'program_1.py'

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It's a boring name, but you know what, that's fine.

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Now, in this program, I want this to do a few things.

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I want it to ask for a sentence.

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I want it to print the length of the sentence, sentence.

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And then I want to write the sentence to a file.

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And actually, before that, what I wanted to do is ask for

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a file name, and we're just going to make sure that it's always a 'txt'.

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So just ask for the file name, but don't add the extension

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in there. And then write that sentence to the file, to the

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file, and then run the program from your command line.

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Now, this sounds like a lot, maybe, but it's actually really

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easy. The reason I wrote this out, is because these are actually steps

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for me. As a developer, I like to see these steps in front of me.

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Okay, so for my first step here, I'm just going to ask for a sentence,

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then print out the length of that sentence, and then I'm

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going to ask for a file name, write that sentence, the first

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sentence to the new file name, and then run the program from my command line.

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So this is actually a lot easier than we think it's going to be. So

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let's say 'sentence = input("Enter a sentence")',

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and then we can print out length.

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Oh, I hit something there. I did not want to run.

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We can print the length of 'sentence', and then we can

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ask for a file name.

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So 'file_name', not a 'file_bane', but a 'file_name =

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input("Enter a file name")'

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Now, I'm automatically going to append '.txt' to this,

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so whatever that 'file_name' turns out to be, I'm going to

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do 'file_name', because it's a string

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we know it's immutable,

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so we're just going to replace the first 'file_name' variable

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with the second 'file_name' variable,

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and I'm going to use an f-string for this. 'f"file_name.txt"',

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and for an f-string we put this in curly braces.

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[no audio]

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So we ask for a 'file_name', and then we need to write the

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'sentence' to a file.

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So let's go ahead and do that. 'with open(', whatever that 'file_name' is going to be,

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So let's go ahead and throw the 'file_name' in here because

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it's a variable, it's a reference.

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So this 'file_name' is going to point to here, which is going

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to point to here, which is going to point to here, which

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is going to be whatever you call your 'file_name'.

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We want to open it in the write mode 'as f'. 'f' for file.

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So 'f.write()', whatever that original 'sentence' is, that's

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this one up here.

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So whatever that original sentence is, it's going to go into

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this file. Then we do 'f.close', and we can print our file is done.

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"You've written", let's say the length of the 'sentence',

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so '', which we have not assigned yet.

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[no audio]

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This is going to be an f-string.

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"You have written characters to", and then

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the 'file_name', ''

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Now we just need to run this. Make sure this exists.

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So let's throw this into a variable as well.

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'sentence_length = len(sentence)', whatever

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that user ends up writing.

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And we don't need to print this because you can see there's two of them,

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[no audio]

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so when I highlight it in VS Code, it highlights over here,

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it's the exact same.

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So we can just use 'sentence_length',

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because it's the exact same anyways.

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[no audio]

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Now what I'm going to do is open up my terminal,

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my command line.

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If you're on Windows, you might want to use 'cmd', 'cmder',

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PowerShell, whatever sort of command line tool you want to use

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on Windows, and on Linux you're going to want to use

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bash or if you have something custom in there, you'll want to use that.

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Now I save this file to my Desktop.

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You can see that I'm in 'Users',

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'kalebtaulien', 'Desktop', 'program_1.py'.

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Now, the reason there's a video in this course, a crash course

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lesson on using the command line is because we need to use this.

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If I do 'ls -la',

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[no audio]

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where is my Desktop? Right there.

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So I can do 'cd desktop', 'ls -la'. Here's my 'program_1.py'.

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And all I have to do,

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well, first things first, I'm going to make sure I'm using

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the right version of Python,

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Python 3.7.2. I use 'python', and then 'program_1

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.py', that's the file name.

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And I'm going to run this, and it's going to say, "Enter a sentence:"

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Hello this is a sentence.

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Okay. 24 characters.

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"Enter a file name".

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'test_file_name'.

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I've written 24 characters to 'test_file_name.txt'.

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Let's do 'ls -la'. Hey, look at that.

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'test_file_name.txt'.

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Let's go ahead and open this in VS Code.

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There it is.

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24 characters.

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This is the sentence.

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And that is our very first Python program.

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And we're actually using a lot of things we've already used.

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We're using 'input'.

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We know it's a string.

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We're using an object property because it has a length.

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This one had 24 characters.

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We're using the function 'print', which is going to print the length.

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We have a 'file_name' in here.

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Again, we're using the 'input' function to grab someone's

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'file_name'. I need to add that space in there, that will drive me

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nuts. And then we're overwriting a string because a string

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cannot be changed.

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We have to overwrite the string.

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And so what we're doing, is we're saying there's going to be

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a new 'file_name' variable. But before this whole line is

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executed, it's going to reference this one.

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Now, this one actually already exists.

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So before creating this one, Python says, "Okay, I'm going to use

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this one that links to here and whatever that value is going to be.

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So that 'file_name' uses an f-string to take that 'file_name'

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and append '.txt' to it.

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So we're always going to write a '.txt' file.

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Then we opened up a new file handler with whatever that file

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name is going to be, based on whatever the user wrote with

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write mode enabled 'as f' for the file handler.

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Then we wrote the original sentence, the first input into that file.

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We closed it because that is a very good practice.

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And then at the end, we said, with an f-string, "You've written

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24 characters to the file name of what was it,

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'test_file_name.txt'.

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And that is a Python program in a nutshell.

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Now, what I would like you to do is create some sort of program

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that's similar to this.

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You can even write the exact same program if you like.

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I would just like you to get some hands on experience with

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using multiple different things in here.

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So we've got 'input', strings, object properties, files, f-strings.

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We've got all sorts of stuff in here, and we're sort of starting to

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put it all together.

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Don't forget, you can always just download my code, and execute

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this as well, and tinker around with it.

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If you're not totally confident with being able to write

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this right now, that's okay.

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A good way of learning is taking code like what I have, and

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just modifying it piece by piece, seeing how it changes when

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you change something.

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So go ahead, give that a shot.

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And when you're done, we can move on to that next lesson.

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Oh, and one last note, your program does not need to be complicated.

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It does not necessarily even need to have a file handler in there.

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Your program could just be something super simple.

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It asks for a name and says, "Hello, name".

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So don't feel like it needs to be super complicated or like,

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you need to impress anyone.

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This is all just for practice

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anyways. Good luck.

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And I will meet you in the next video.