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In this video, I want to discuss strings in a bit more detail,

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and also introduce the idea of storing values in variables.

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We'll cover variables in the video after next, but I'll actually introduce them here.

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So we'll continue using our HelloWorld project, but let's create a new Python file for this video.

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So we're going to open our project pane.

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I'm gonna right click on the project name,

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click on New and choose Python File,

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and I'll call this one strings.

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And I'll just close the project pane by double clicking on the file name here, strings.py,

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so we can see what we're doing.

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Now in Python, strings can be enclosed in either double or single quotes, as I've mentioned previously.

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Let's just go through and type in a couple of examples, noting that these are all valid

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Python strings. So the first one we're going to
start with, "Today is a good day to learn Python".

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You can see that's valid. Next line, using single quotes, "Python is fun".

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Next line, print double quotes Python
single quote s strings are easy to use,

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and on line 4 I'm going to type print
parentheses again,

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single quote, We can even include double quotes, quotes, in strings. Alright.

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So unlike some other languages like Perl, there's no difference between single or double quotes in Python.

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However, if you start a string with one type then you must finish it with the same type, and

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we've talked about that previously.

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If you need to include a single quote in a string, then use double quotes to enclose the string,

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like in the third example above.

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And similarly,

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if your string will include double quotes, then enclose the string in single quotes, as we've done on line 4.

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Now we can also concatenate strings to make longer ones, using plus.

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Let's go ahead and type print parentheses double quotes hello +

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double quotes again, world with a space at the start there.

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So that joins the two words together, to make the single string, hello world.

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So that's called string concatenation.

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Python isn't going to perform addition on the two strings. It just joins them together or concatenates them.

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So I'm gonna run the program to check that it prints what we expect.

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But remember to check the drop-down in the top right hand corner,

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and right-clicking the editor to run the correct program, otherwise you'll run helloworld.py by mistake.

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So if we do that without changing that, and run it,

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note that we're getting the Hello World output, and not the program output from this program,

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which could be a bit confusing for you. So you want to right-click in here instead,

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click on run the first time.

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By doing that, we're now running this program, and noting that in the top right hand corner,

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the drop down has now, or is now showing strings, being the current program that we're running.

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And you can see that in the case of line 5,

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we've got hello world showing - the
two strings concatenated together to form one string -

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and we've got the single quotes and double quotes showing, as per the examples on lines 3 and 4,

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and the rest of the text, as per what we've set up.

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Alright, so we can also store the strings in variables, and then concatenation makes more sense.

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So let's go ahead and do that.

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So we can come down here,

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and I can type greeting equals Hello in double quotes, name equals, we'll type Bruce in double quotes.

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I'm gonna put a comment here, hash, if we want a space, we can add that too.

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And we type print left and right parenthesis, and within the parentheses we can type greeting,

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noting that I've just typed a g and IntelliJ helpfully gives us a menu that we can select from, and if we've got the

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menu options selected that we want, we
can use the up and down arrow keys, by the way.

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But greeting is what we want. I'm going to press ENTER there. That saves us a bit of typing.

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So I can then add + single quote with a space in it , + I can put it in n for name, press ENTER,

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and if we run the program now,

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we can see the strings have been concatenated to produce the output.

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So to make this even more useful, we could use the input function to read in a name from the keyboard.

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So let's go ahead and do that.

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So where we've got name defined on line 7, let's change that to be name equals,

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and we'll delete the text Bruce in double quotes

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and instead we'll make an input parenthesis double quotes, Please enter your name, and a space.

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Then our closing double quote and right parenthesis.

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The input function displays the text provided to it, then waits for text to be entered at the keyboard.

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So I'm going to right click and run the program.

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Now when you run the program, click into the run window with the mouse,

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or you can use alt 4 on a PC before typing your name.

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So I'm going to come into here and I'm just going to double click it.

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I'm going to type Tim with a capital T.

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When you press Enter, the text you typed
is stored in the variable name.

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This is the code on line 7 and then used by the print function to show the greeting.

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So if we press ENTER, we can now see the output, Hello Tim.

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So that's pretty cool. Our programs can get input from the user. To do that we call the input function,

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and then assign the value it returns to
a variable.

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I mentioned function return values, in the slide at the end of the last video,

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so here the return value of the input function, is whatever text the user enters.

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So we assign that to the variable,
name on line 7.

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Assignment is done using the equals symbol, and anything on the right of the equals symbol is evaluated first,

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before the assignment happens.

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So looking at line 7, that means the input function is called first.

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When it finishes, which happens when the user presses enter,

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the value it returns is assigned to our variable name.

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So let's actually come in here and type in print below the input line, print greeting,

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I probably should have done this before,
greeting + name,

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because I've added the space down here on line 11, but I didn't do it on line 8 to show you what it's like without the space.

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So let's run that again.

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Click into the run window, Tim, and you see HelloTim without the space, and also Hello Tim with the space.

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So as you can see now, on lines 8 and 11,

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the value of name is printed out.

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Name isn't enclosed in speech marks, and again that's because it's not a string literal.

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It's the name of a variable, and Python uses the value whenever it sees the name, name in our case, in our code.

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We'll talk about variables more, in a video after the next one.

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First though, I want to finish discussing strings by looking at the escape character,

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and we'll be doing that in the next video.