WEBVTT

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Before we move on with the course,

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I want to demonstrate what we talked about in the previous lesson, and I

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will do that by introducing the concept of void pointers.

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So what is a void pointer? In a way, this is the purest kind of a pointer

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because it doesn't have any specific data type attached to it.

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This pointer literally only holds the memory address,

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and there are no strings attached.

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I created two pointers.

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One of them is int, and the other one is void, but they both point

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to the same place in memory, to the variable, x.

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I will print out both of them so that we can verify this

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claim. As you can see, both of the pointers store the same

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memory address, which was expected.

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But what will happen if we try to dereference them?

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You can already see that my editor is warning me, but we'll compile

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it anyway. And it seems like there's an error.

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Void pointer is not a pointer‑to‑object type.

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If you remember the previous lesson, this makes sense.

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When we try to dereference this integer pointer,

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the compiler will know that it should also look at the following three

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bytes in memory because integer values are four bytes long.

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But when we try to dereference a void pointer,

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compiler will produce an error because there are no void variables.

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If you want to dereference pointers,

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the compiler needs to know which data type are they pointing to.

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So, if we cannot dereference void pointers,

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why would we ever use them? Void pointers can be used as a

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placeholder or an interface for a piece of code that we want to

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apply to multiple different types of pointers.

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You will see an example of this in the last lesson of the module.

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We have a memory address of this variable, x,

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which means that we can simply cast this void pointer into an

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integer pointer before dereferencing it.

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And now, if I recompile the program,

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you can see that everything works as expected.

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Now you can see why data types in pointer declarations are

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important. And now that we know all of this,

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we can finally move on to dynamic memory allocation.