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So far in this course.

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Initializer list have been treated as a kind of C plus plus 11 construct.

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And a bit like the bulletin arrays.

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So, in fact, when you use the initializer list syntax using the braces here, the compiler actually

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creates an instance of the templated initialize list class here.

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So if an initializer list is used to initialize another type, for example, in this case the vector

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here.

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Uh, then the compiler creates an initialize list object and with the given values between the braces

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here, so and the container object is initializing the initializer list iterator.

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So this ability to create an initialized list object from a braced initializer list can be used to give

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a function a variable number of parameters.

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So I'll beat all of the parameters.

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Must be the same type in this case here.

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So in order to use this initializer list, we have to firstly include the initializer.

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Initializer list.

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Header file here.

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And then we're going to create a new function named sum and.

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But you can return the integer here.

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Sum and initial.

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List here and.

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Then.

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This initializer list will take the integer values here and make it values.

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So this sum here takes the parameter values.

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This will take one parameter and the type of initializer list integer here.

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So which here integer sum equals zero here, for example.

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And we're going to create a for loop integer values.

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We're going to iterate throughout this parameter.

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Values.

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And with this for loop.

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We're going to use this as the we're going to some increment, some by one at every or some by e here

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at every iterating here.

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And we're going to after this, we're going to return the.

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Add some integer here.

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So in the main function we're going to create, we're going to make actually the main function is going

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to just print something and call this some, uh, function here that we created here.

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So C out.

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Some.

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Here and.

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End line.

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Firstly, we're going to call just an empty sum and see out sum.

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Here we're going to pass the values here.

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In this case, we're going to pass the negative values starting from six minus six, negative six here.

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Five, four, three, two.

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One and here and line.

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So.

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C out.

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C out.

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Some.

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And this case we're going to make give it a ten, 20, 30 and end line here.

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So in this case, we're going to get the if we pass the NON-OBJECT to this some function, we're going

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to get a zero.

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In this case, we're going to get the -2021.

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And in this case, we going to get the 16, as you can see here.

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And the sum function here has a single parameter initializer list integer here, which can only be initialized

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with the list of integers here.

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So the initializer list class has a very few functions because it only exists to give access to the

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values in the brace list here.

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So most significantly, it implements a size function that returns the number of items in the list here.

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So you can use values that size.

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As you can see, this will return the number of items in the list.

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Let me mention it.

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So when you download this code, you're going to see.

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Returns, number of items in the list.

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So here.

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And size function returns the number of items in the list.

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So.

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And the begin and end functions in return pointer to the first item in the list and to the position

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after the last item.

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So these two functions are needed to give iterator access to the list and it enables you to use the

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object with with the range for loop here.

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So as you can see here, we when we compile the code, we're going to get the zero -20.

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Why 21 and 60 here?

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So in this example, the main function here calls this function three times the sum function, three

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times each time with the priest initializer list here, as you can see here.

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So and the function will return the sum of some of the items in the list here.

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And as you can see, it, will the sum here multiply or will some of the numbers in the list?

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So clearly, this technique means that the each item in the variable parameter list has to be the same

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type or type that can in can be converted to a specify specified type.

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So you will have the same result if the parameter had been vector.

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And the difference is that the initializer initializer list parameter requires the list initialization

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here.

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So if we make it like this two point make, give it the 2.1.

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As you can see here, we are going to get error because the initializer list can only you can just only

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pass the values that has the same type as this parameter here.