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Memory and the C++ standard library here.

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This C++ Standard library provides various classes to allow you manipulate collection of objects.

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These classes called the s t L Standard Template Library.

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So this provides a standard way to insert items into collection objects and ways to access the items

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and iterate wrote entire collections.

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This is called the Iterator.

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Here, the SDL defines collections classes that are implemented as Quest stacks or as a vectors with

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a random axis here.

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These classes will be covered in depth in the next lecture.

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So in this section we will limit the discussion to just two classes that behave like C++ built in arrays.

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The first let's get began with the standard library arrays here.

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The standard library arrays provides two containers that given random access via an indexer to the data.

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So these two containers also allows you to access the underlying memory size they guarantee to store

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the items sequentially and contiguous in memory.

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And they can be used when you are required to provide a pointer to a buffer.

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So these two types are both templates, which means that you can use them to hold built in in the custom

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types.

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So these two collection classes are array and vector here.

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Yeah.

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So these are.

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These are the builtin standard.

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Library.

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All right.

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So we can also use the stack based array class in C++ here.

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The array class is defined in the array here, like that array header file here.

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So the class allows you to create fixed size arrays on the stack.

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And with the built in arrays, they cannot shrink or expand at runtime.

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So since they are all located on the stack, they do not require a call to a memory allocator at runtime,

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but clearly they should be smaller than the stack frame size.

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So this means that an array is a good choice for small array of items, so the size of an array must

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be known at compile time.

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And this is passed as a template parameter like that here, for example.

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Let's include a include array here.

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Array and array.

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Here, Integer four.

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And here, 1 to 3.

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Four.

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So in this code, the first template parameter in the angled braces is a type of each item in the array,

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and the second parameter is the number of items.

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So here number of items and the type of the each item in the array here.

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So this code initialize the array with an initialize list, but not that you still have to provide the

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size of an array in the template here.

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And this object will work like a built in array or indeed any of the standard library containers with

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the range loop here.

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So let's create a range load here integer E and here we can reset the array here, make it here.

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Right here, and we're going to create the array in the jar.

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There.

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Firstly, we're going to create the array like that.

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Yeah.

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And we're going to pass iterate fraudulence error here at.

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And each time we're going to print this on the screen.

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We have to import and use the namespace here.

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And rent it out.

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As you can see, we printed our variables here.

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The reason is that all implements the begin and end function that are required for this syntax.

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So you can also use this like that here.

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For example, for integer E zero opps integer E equals zero, while E is less than R that size here

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and plus class E here and C out here are right here are error E and and line here.

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We can write it also like that it's the same output here, the size function here.

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As you can see here we return the size of the array and the square braces.

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Indexer gives the random access to the members of the array so you can access the memory outside of

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the bounds of the array.

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So for the previously defined array that has four members you can access like this array or that ten.

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So this may cause the unexpected behavior at runtime.

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Let's try it out.

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As you can see here, there's a just reprint.

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There's a bunch of zeros.

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Here.

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So or this may cause unexpected behavior or even some kind of memory faults.

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So to guard against this, the class provides a function at which will perform perform a range take.

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And if the index is out of range, the class will throw the C++ exception which here.

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Here.

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C++ exception named out of range here.

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So the main advantage of using an array array object is that you get compile time checks to see if you

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are inadvertently passing the object to a function as a dump pointer here.

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Let's make another example here.

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Void.

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Here.

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Void use pen in its.

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An integer pointer here.

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So at runtime the function does not know the size of the buffer pass to it.

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And in this case, the documentation says that you must pass a buffer with ten integer types.

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Variables.

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But as we see in C++ allows, you allows a built in array to be used as a pointer.

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So we can do it like that.

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In practice use.

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Ten.

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Ah one.

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So, Ops.

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Here.

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So let's create another array for this example and make comment out.

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Common theme here.

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Okay.

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Integer array.

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Yes.

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And one, two, three, four.

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This contains the same variables as previous arrays here.

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And then this will read the past the end of the buffer here.

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As you can see here, we got an exception.

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So this is no compiler check or nor any non runtime check to catch this error.

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But there is the already class will not allow such an error to happen because there's no automatic conversion

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into a the pointer here.

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So if you're interested in obtaining a dumb pointer, you can do this and be guaranteed to have access

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to data as a contiguous block of memory where the items stored sequentially.

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So you can do it like that.

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Here.

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Let's compile it.

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And, uh, here.

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We got a letter turned from some comment filed.

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That's why you don't have to do this like that with a thumb pointer here.

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And we can.

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Testify like that here.

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I was one.

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And data here.

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And as you can see here, this won't compile either.

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So this is not the correct, correct coding style here.

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And you will learn more about and how to correct this syntax in next lecture.