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Welcome back.

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And this video, I would like to talk about typecasting and very quickly look at lists, so I have this

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function main here.

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And this typecasting file in which I create a new variable called string list and it is a list of strings.

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So that is the syntax that you can use.

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And when you want to create a list, then you can use a list of, for example.

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So I'm creating a list of Dennis, Frank, Michael and Gary.

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So this is a list which can only contain strings, but you can also create a list which has a mixed

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types.

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For example, using the any keyboard here, we say that we accept any type of object in our list.

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So here we can use strings, then we can use integers, but also doubles and any other data type that

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is available.

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So let's look at this for loop here.

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We have value and mix type list.

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So what we do is we go through this mix type list with this fall.

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And for every single value in that mix type list, we want to run this, if else, block.

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So we check if the value is of type integer.

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So we use this is keyword here, is it?

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And if it's an end, then please print integer and then the value.

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Otherwise, if it's type double, please.

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Right, double than the value with the floor value, so we floor the value to its next lower full number.

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And otherwise, if it is a string, then please write the string and also write the length of the string.

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So just write this print statement and in any other case.

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So in this blog, I just say it's an unknown type, so I have no idea of what type it is.

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All right.

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So this is a follow up.

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Alternatively, we could have done it with this for loop here, where instead of using if and else,

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if we use went and it works pretty much the same way, only the syntax is different.

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So can see we use when the value and then in brackets we say is integer, then execute this code.

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So what we have here is a bunch of lambda expressions.

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And you can also see once you hover over this if statement that it wants you to use when instead.

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So it's pretty much doing the same thing as we have done here and this alternative way.

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So both ways are fine.

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But Caitlin prefers this one approach.

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Now just look at smart casts.

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A I smartcast is what you can see here.

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So I'm creating this value, which I call object one.

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It's a variable which is of type any, and it says I have a dream.

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All right.

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So I store a string in there, but no check is object one a string, and I'm using the exclamation mark

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here.

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So this means is it not a string, so is object one and not a string?

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Then I'm going to say print another string.

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Otherwise, I know that it's a string.

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So object is automatically cast to a string in the scope.

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So I'm saying found a string of length object at length.

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So it already knows OK because it is a string we can use it string functionality, such as getting the

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length of their variable.

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Then there is something called explicit unsafe casting using the key word.

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This can go wrong, by the way.

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So we have this other variable called SDR one, which is of type string and what it tries to do is it

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tries to use object one as a string.

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So this will only work if object one is in fact a string.

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If not, then this will go wrong.

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So what we're doing is we're using it as a string, we're storing it.

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It's an SDR one, and then we print the length.

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Then we have this other object here, which is of type any again, and we're storing this time an integer

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in there.

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And what we're trying is about string string object, a string.

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So what we're trying to do is to make a string out of this object to.

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And then we're printing it.

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As I said, this is unsafe casting, this can go wrong.

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And then we can also use explicit essays casting using the ask question my keyword, so here object

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three.

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Any again, the same value and this case we say, OK, it's a string Nullarbor and Object three as high

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strength.

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So does it work or does it not work?

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Well, in this case, it will work.

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So if we use that, it will print.

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Now what will happen here?

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Well, let's find out.

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We can just run the code.

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And see, so I'm getting an error here, exception and main thread typecast, Katie 47's on this line

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here where I'm saying object to a string.

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Why does it go wrong?

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Well, because object to is of type any and what is behind it.

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It's not a string.

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It's an integer.

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That's why this call doesn't work.

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If I, for example, would go ahead and add the question mark here.

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Well, now it's not working because the string is not another string.

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So I would have to make this also another string and suddenly it would work.

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But that's exactly what we did in this case down here.

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All right.

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So let's get rid of this line here, because it doesn't add any value.

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And let's run it again, and there we are.

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So now things work.

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Let's start from the top.

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We say here at the very top.

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Starring Dennis.

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Of length.

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Five.

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OK, so we had this mixed type list, so we go through every single element.

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Then the next element is an integer 31.

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Then it's an integer five, a string b day with the length of four, then a double seventy point five

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with the floor value of seventy.

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And then string ways of laying six string kg of length to.

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And then again, the same with this second for loop, so.

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Exactly the same stuff.

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And then we are at this point here where we smartcast.

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So.

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It sets forth a string of length 14.

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And that is this else plot, because we are saying here that I have a dream is not, not a string.

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So we go into this book and we print this statement out here.

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Then we have this statement where it says object as a string and its length is 14, so object one.

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What its object one well is, I have a dream.

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So of course, its length will be 14.

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And then finally, we have null.

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And where does this now come from?

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Well, it comes from here where we are trying to save casts and we use Nullarbor.

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So our R3 is a Nullarbor, so it can be now.

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And we're trying to cast when we are not sure whether it's going to work or not.

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And in this case, we were wise to do so because otherwise we would have created an error as we have

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done.

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And the example with Object two?

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All right.

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So this is a little introduction to typecasting.

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Thanks a lot for your attention.