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Before we start, did you try solving the workbook yourself?

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If not, please click the link in the resources folder and follow the instructions for this workbook.

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Welcome to Workbook 6.12 and this one you decide to play the lottery and you're feeling good about these

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numbers.

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I guess you had a dream about them or something, and now it's telling us use a raised copy of to copy

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all the elements of ticket into ticket two and then change the third value to 54.

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Now what I'm going to do actually is the exact opposite.

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Instead of copying every value from ticket into ticket two, what I will just do is set ticket to equal

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to ticket.

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And if I were to change the value at index 2 to 54, what do you think would happen?

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Let's visualize the runtime and find out.

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So the variable ticket is zooming in.

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You'll see that it stores a reference that points to an array.

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If you set ticket to equal to ticket, all you're doing is copying over the reference.

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So now take it two shares the same reference at ten, pointing to the exact same array.

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So whatever changes I make through the ticket to variable will also affect ticket.

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Isn't that crazy?

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So this is the reference trap by setting ticket to equal to ticket.

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All we're doing is copying over the reference that points to the exact same array.

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That's no good.

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What we need to do is instead of copying over the reference copy over all the values, which means we

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can say erase copy of.

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We're going to create a copy out of the original array and we're going to copy the full length of the

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array.

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All right, So if we try this again.

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Ticket store is a reference that points to this array.

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Ticket to.

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Store is another reference that points to a copy of the original array.

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So now if I change, the state of ticket to ticket remains unaffected.

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And it's very nice that breakpoints allow us to visualize the fact that the variable store is a reference

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that points to an array at ten points to one array at 12 points to another array.

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Task number two, create a function that prints the ticket numbers.

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All right, so the function name is print ticket numbers.

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It's going to be void, but it will take an one parameter of type int So public, let me zoom out a

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little.

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Public static void print ticket numbers.

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Event tickets.

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First thing we do is use a loop to print the ticket numbers in one line.

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So we create a loop that runs through the length of the ticket array.

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I is smaller than ticket length.

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Plus plus.

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Then we just copy over the following.

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After the loop.

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Print two new lines.

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Simple enough.

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And now we call the function for each ticket.

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So here we will say.

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Print ticket numbers for ticket one.

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Here we print the ticket numbers for a ticket to.

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All right.

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The variable ticket store is a reference that points to one array.

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The variable ticket to stores, another reference that points to a copy of the original array.

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Here.

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We're just going to print the numbers for the first ticket.

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And here we print the numbers for the second tickets.

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All right.

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That was all.

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The take home message is never set a raise directly equal to each other.

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Because if you realize that each variable stores a reference that points to an array by setting ticket

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to equal to ticket.

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All you're doing is copying over the reference.

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So now two variables share a reference to the same array.

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So by virtue of making changes through ticket to ticket is going to get affected as well.

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This is not good.

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Instead, what you should do is set this variable equal to a copy of the array.

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And that is all.