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Hello and welcome.

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In this lecture we are going to create the method for the equals two button.

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So it will capture all the events that happen when the equal to button is clicked so less create these

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color code to do that.

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You click on the equals two button.

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And here in the properties click on that and where you've got the click event just double click.

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And it should open up the skeletal code.

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So this is the method.

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And in between these parentheses here is where we will write our code that will respond to the equals

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two button when it is clicked because the equals two button will be used in combination with the operators.

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We are going to use what is called a switch statement the switch statement basically is used to perform

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different actions based on different conditions.

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All right.

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So what happens is that when you use a switch statement you select a block of code to be executed based

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on certain conditions.

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The best way to illustrate this that I'm going to just write a piece of code and I will run through

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it with you.

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All right.

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I have added a chunk of code here this code highlighted here.

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And this is basically what is known as a switch statement.

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So a switch statement is used to perform different actions based on different condition.

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So here when you are writing a switch statement you begin with the word switch and then in inside the

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parentheses you have to pass in an expression that will be evaluated once.

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All right.

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So this what have passed in here is a variable that was created here.

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This string here called operate all clicked.

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So that is a variable that is the expression this switch is is going to express is going to see what

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happens a wrong the code goes true once and it checks this to check which of the operators have been

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clicked.

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So each of the operators are represented as cases.

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So this is case one if for example someone clicks on the does a mathematical addition.

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And after that they click on the equals to sign this.

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It will references operator or clicked variable and the case will be plus for example with the operator

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on perform is a plus it will execute this code.

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This result box dot text is the variable is the result box where the answers are displayed for the calculate

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and we'll set that to equals to the resulting value variable plus this double here we used in the past

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to convert the text from the result box into a value that it understands.

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And then we are now.

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Then we convert and after that's been converted we then converted into a string using the two string

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method.

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So this is case 1.

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So if the operator that is click is a plus it will execute this code once he's finished doing that.

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It will break.

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That means the code will be terminated and then it looks for the second case.

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If another operator is performed if it's a minus.

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It will execute this piece of code here.

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Identical to the first one.

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Once it's done that it doesn't hang about it breaks out of the code.

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Again the next one is a multiplication.

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If each of these block code blocks are represented by as a case.

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So this is a first case second case third case.

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So if the operator clicked if it's a division if it's on a division operator it to execute this piece

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of code here.

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Okay.

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And then with a switch statement you sometimes have what is called a default.

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The default keyword basically specifies the code that will run if there is no case match.

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OK.

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So if none of the scenes here matches the expression you have to specify default which would be the

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code that will run the default case does not have to be it doesn't have to be the last case here.

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You could place it anyway in the block OK.

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However if the default is not the last case in the switch block you must.

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And the default case with a break although I've done that here is not really necessary.

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But if for example the default was somewhere in the middle you'd have to end it with a break once again

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our run through the switch statement with you.

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So the way the switch works is that this switch looks for an expression.

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In this case the expression is this variable here.

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It will evaluate that expression once the value of the expression is thin compared with the values of

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each of the cases for example plus minus two times more division.

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It would compare that to each of the values in the cases and if there is a match the associated block

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of code is executed.

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If you find the matching goes through the cases if there is a match it will stop and execute that course

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code piece of code once a match is found it it hits the break and the the code stops the execution of

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the code will stop when a match is found and the job is done.

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The break stops and there will be no more evaluation of the code block.

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Note that is not always necessary to put a brake in the last case.

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For example if you have the last case in the switch block you don't necessarily have to put a brake

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is just good practice.

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In this lecture we wrote the code for the equals two button is in the switch statement.

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So there's still a bit more to do so we'll continue in the next lecture where we will try and tie up

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the rest of the code that will make the calculator all active.

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The purpose of this lecture was just to write the piece of code for the equals two button which we have

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done using this switch statement.

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Thanks so much for watching.

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Take care.

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Bye for now.