 So let's have a look at substrings So I'm going to introduce this new computer variable called str underscore Subset just by my choice and inside of it. I'm going to put the string. I love Julia exclamation mark I use the semicolon so it does not there's no output to the screen First things first, let's count the number of characters in our little string and we use we've seen this before the length Function and inside of that the argument is this computer variable str underscore subset If we run that we see there are 13 and indeed if we counted we notice that we have to count the spaces So it's one two three four five six seven eight nine ten eleven twelve thirteen thirteen characters Now let's do a little loop just so that we can see what happens Now what I'm going to do here Let's just bring that up a little bit. I'm going to say for I in one to the length of str underscore Subset that means 13 so for I in one two thirteen So it's going to loop through one two three four until we get 13 print the following the following that I wanted to print is a String and the strings is character and then it is this placeholder dollar I so the first thing is going to say character one the next next time it loops it's going to say character two and Then is Space colon space then a tab Remember this column in this comma concatenates all of this into one. This is a tab so that is code for a tab comma and then the subset String subset I now this is Notation for the index of that So this I love Julia exclamation mark It each and every character in that sentence has an index and then comma we're going to have this is a new line So I've just told you there the comma concatenates the whole the commas concatenate the whole lot the Backslash t as a tab and the backslash n is a new line Let's execute that so you see what happens and indeed there we go So says character one is an eye character two is a space so space counts and that's how we get to 13 with the exclamation mark So we've seen this index thing. Let's let's slice things up a bit So I've still got this computer variable string str underscore subset and I want from Index one to six so note these are square brackets and one to six and that is I love So it's one two spaces two three four five six one two six those characters Let's see what happens if we take eight till the end I know the end is 13 But in case you didn't know what the length of your string was you could just use end so eight to end What's this gonna be Julia exclamation mark? Let's reverse the order. That's a bit of fun. So this says go from end To the first one But go back in steps of negative one so we're gonna take our string and just reverse it and that's quite clever I think that's quite clever. So I love Julia exclamation mark all in reverse Now just note the following just in case you do run into this. Let's Correct that spelling mistake there that looks a lot better now note if we just use one just going to the index one Which is just going to be I and see it has single quotation marks versus if I say one to one I'm gonna get the double quotation marks now. We're going to look at this a bit later the single quotation marks refers to this as a character a certain character and this is just part of a string by The double quotation marks later on we'll see the single quotation marks. They are all about characters and that is up next