Name: C++ 中的指針簡介，指針教程，C++ 指針 (Introduction to Pointers in C++, Tutorial on Pointers, C++ Pointers)
Uploaded: 2025-05-27T13:51:53.000Z
Duration: 11 min 38 s

未來簡單式

Okay, so in this video we're going to take an introductory look at pointers in C++.

在本視頻中，我們將介紹 C++ 中的指針。

好吧，那麼到底什麼是指針呢？

A pointer is just simply a data type that points to another value stored in memory.

指針只是一種簡單的數據類型，它指向存儲在內存中的另一個值。

So let's look at a logical representation of memory here in which we have some addresses, we have some values associated with particular address locations, and we also have some variable names here.

是以，讓我們來看看內存的邏輯表示法，這裡有一些地址，一些與特定地址位置相關的值，還有一些變量名。

So we have this variable named p associated with this particular value, we have the variable named x, which is associated with the value of 25 here.

是以，我們有一個名為 p 的變量與這個特定值相關聯，我們有一個名為 x 的變量與這裡的 25 值相關聯。

And we're going to assume that x here is an int variable, and we'll assume that p is a pointer variable.

我們假設 x 是一個 int 變量，p 是一個指針變量。

More specifically, we could say that p is an integer pointer, meaning it's capable of holding addresses or memory locations associated with integer values.

更具體地說，我們可以說 p 是一個整數指針，這意味著它能夠保存與整數值相關的地址或內存位置。

So we can see here that the address associated with x here is the address 0003, and that in fact is the value that's being stored here at this particular memory location associated with p, our integer pointer p.

是以，我們可以看到與 x 相關聯的地址是 0003，而這實際上是存儲在與 p（我們的整數指針 p）相關聯的特定內存位置上的值。

So p here is able to reference this particular memory location, and if we're able to get to that particular memory location, we can also get to the value that's stored at that particular memory location.

是以，P 可以引用這個特定的內存位置，如果我們能夠訪問這個特定的內存位置，我們也可以訪問存儲在這個特定內存位置的值。

And right now this may seem like a very convoluted way of getting to the value of x, since we simply have x over here, why not use it?

現在看來，這似乎是獲取 x 值的一個非常複雜的方法，既然我們這裡有 x，為什麼不用它呢？

And in this particular case we could and we should use x, we shouldn't be introducing a pointer unnecessarily.

在這種特殊情況下，我們可以而且應該使用 x，不應該不必要地引入指針。

But later on we're going to see examples where we're going to need pointers.

但稍後我們會看到一些需要指針的例子。

There's no way for us to get around not using pointers in many situations in C++ programming.

在 C++ 編程的很多情況下，我們都無法避免不使用指針。

So the big idea here is just to know that pointers are a data type, and they hold addresses of other values in memory.

是以，這裡的要點就是要知道指針是一種數據類型，它可以保存內存中其他值的地址。

All right, so now let's look at the syntax for declaring a pointer in C++.

好了，現在讓我們來看看 C++ 中聲明指針的文法。

So just like you declare any other type of variable in C++, you have to specify both a type and a name.

是以，就像在 C++ 中聲明其他類型的變量一樣，您必須指定類型和名稱。

Except now, whenever you specify the type, you also include this asterisk here.

但現在，無論何時指定類型，都要在此處加上星號。

So if we were wanting to declare an int pointer, you would specify the type int, then this asterisk here, which we would read as pointer, and then whatever the name should be.

是以，如果我們要聲明一個 int 指針，就需要指定 int 類型，然後是星號（我們將其理解為指針），最後是名稱。

So once again, we're just specifying both the type and also the name here.

是以，我們在這裡再次指定了類型和名稱。

And depending on what book you read or if you look at code online, you may see this asterisk here sitting either next to the type or immediately to the right of the type, or it could be immediately to the left of the name.

根據你閱讀的書籍或在線查看的代碼，你可能會看到這個星號位於類型旁邊或緊靠類型的右側，也可能緊靠名稱的左側。

And either version of this is fine, so the C++ compiler has no problem examining this and being able to decipher exactly what's going on, that you are in fact declaring an integer pointer.

無論哪種版本都沒有問題，是以 C++ 編譯器在檢查這一點時不會有任何問題，並能準確地解讀出到底發生了什麼，事實上你聲明的是一個整數指針。

This is my preference, though, because I like to be able to read this as int pointer, and this just simply being the name of the pointer.

這是我的偏好，因為我喜歡把它讀作 int 指針，而 this 只是指針的名稱。

Because any time that we're going to be making use of this pointer p, we'll be using it via its name.

因為任何時候我們使用指針 p 時，都是通過它的名稱來使用的。

And if you want to declare other variables or other pointer variables of other types, you would just specify their type and the asterisk.

如果要聲明其他變量或其他類型的指針變量，只需指定它們的類型和星號即可。

So if you wanted to be able to reference a particular string address, then you would say string, asterisk, space, and then whatever the pointer name.

是以，如果你想引用一個特定的字符串地址，那麼你可以使用字符串、星號、空格，然後是指針名稱。

Declaring a pointer, specify the type, asterisk, space, and the pointer name, unless you want to go with this convention, which is also very popular.

聲明一個指針時，需要指定類型、星號、空格和指針名稱，除非你想使用這種約定俗成的方式，這種方式也很流行。

Okay, so now that we know how to declare pointers, let's take a look at some of the common pointer operations.

好了，現在我們知道了如何聲明指針，讓我們來看看一些常見的指針操作。

The first one we'll look at is the address of operator, and then we'll take a look at the contents of operator, which is also known as the dereferencing operator, and see how those work.

我們首先要了解的是運算符的地址，然後再看看運算符的內容（也稱為取消引用運算符），看看這些運算符是如何工作的。

All right, so let's take a look at an example using the address of operator.

好了，讓我們來看一個使用運算符地址的示例。

And we're going to go back to the original example that we started with when we first started talking about pointers.

我們將回到最初開始討論指針時的例子。

So in this example here, we have this integer variable x, and we have the value of 25 assigned to x.

是以，在這個例子中，我們有一個整數變量 x，併為 x 賦值 25。

So we can imagine here in memory that at some particular location, we're saying at address location 3, that we have this value of 25, and we have the variable x associated with it.

是以，我們可以想象一下，在內存的某個特定位置，我們說的是地址位置 3，我們有一個 25 的值，我們有一個與之相關的變量 x。

Now, what we can do is get this address here by simply using the ampersand, the address of operator, and prefixing it before the variable that we want to get the address of.

現在，我們只需在要獲取地址的變量前使用 "amppersand"（符號，即地址運算符）並加上前綴，就能獲取該地址。

So we're saying that we want to get the address of x here.

所以我們說，我們要在這裡獲取 x 的地址。

So once we have done that, we can assign that particular address to an integer pointer.

是以，一旦完成上述操作，我們就可以將該特定地址分配給一個整數指針。

In this case, we're declaring an integer pointer p, and we're assigning the address associated with x.

在本例中，我們聲明瞭一個整數指針 p，並分配了與 x 相關的地址。

So once we finish this particular line of code here, we would have this logical representation here in our memory.

是以，一旦我們完成了這一行代碼，我們的內存中就會有這個邏輯表示。

So we have this particular value of 3 for the address that's associated with this, so we're indirectly able to get to this particular value.

是以，我們有一個與之相關的特定地址值 3，所以我們可以間接獲取這個特定值。

Now, if we were to go in and do a cout operation, so if we wanted to print out the value of p to the console, remember that p actually holds an address.

現在，如果我們要進行 cout 操作，將 p 的值打印到控制檯，請記住，p 實際上保存的是一個地址。

So what you would see is this value 0003 being outputted to the console.

是以，你會看到這個值 0003 被輸出到控制檯。

And that's pretty much what's going on with the address of operator.

操作員的地址差不多就是這樣。

It's just retrieving the address of some particular variable.

它只是檢索某個特定變量的地址。

Okay, so now that we know about the address of operator, let's take a look at the content sub or the dereference operator.

好了，既然我們已經知道了操作符的地址，那麼讓我們來看看內容子操作符或取消引用操作符。

In this particular operator, it's going to allow us to get values stored at an address held by a pointer.

在這個特殊的操作符中，它允許我們獲取存儲在指針所持地址上的值。

So we have this pointer p, and it holds this address value of 3.

是以，我們有一個指針 p，它的地址值是 3。

And if we're interested in actually getting to this value 25 that's stored at this location, what we have to do is dereference this pointer p by using the little asterisk symbol.

如果我們想獲取存儲在這個位置的值 25，就必須使用小星號來取消引用指針 p。

So here, if we did cout and dereference this pointer p, what we'll do is instead of getting the address here, it actually gets the value that's associated with that address.

是以，在這裡，如果我們使用 cout 並取消引用指針 p，我們將做的不是獲取這裡的地址，而是獲取與該地址相關聯的值。

So we get the value of 25 being outputted.

And this may seem like a very convoluted way of getting to this value of 25 since we have this variable x.

由於我們有 x 這個變量，是以得出 25 這個值的方法可能看起來很複雜。

But later on, we'll see examples in which the only mechanism we have to get to something is through a pointer because it will be an unnamed memory location.

但在後面的示例中，我們將看到我們唯一可以通過指針來訪問的機制，因為它將是一個未命名的內存位置。

We will not have a variable associated with it or a variable name.

我們將沒有與之相關的變量或變量名。

We'll only have a pointer that's associated with it.

我們只有一個與之相關的指針。

I want to talk about how we can dereference this pointer p and it be the same thing or just an alias for x.

我想談談如何取消引用指針 p，使其成為 x 的別名。

So however you think about x being in a particular expression, you could think about dereferencing this pointer p meaning the same thing.

是以，無論你如何看待 x 在某個特定表達式中的位置，你都可以認為取消引用指針 p 的含義是一樣的。

So in this very first expression here, we see that x occurs both on the left-hand side of the assignment statement and also on the right-hand side of the assignment statement.

是以，在第一個表達式中，我們看到 x 既出現在賦值語句的左側，也出現在賦值語句的右側。

So on the right-hand side of the assignment statement, we're saying to get the value that's stored at this particular memory location associated with x.

是以，在賦值語句的右側，我們說的是獲取存儲在與 x 相關聯的特定內存位置上的值。

So we're just simply getting this value of 25.

是以，我們只是簡單地得到 25 這個值。

And then on the left-hand side of the assignment statement, this x here is saying that we want to store this result here at the memory location specified by x.

然後在賦值語句的左側，這裡的 x 表示我們要將結果存儲到 x 指定的內存位置。

So we'd have the value of 30 being stored at that particular memory location designated by x.

是以，我們會在 x 指定的特定內存位置存儲 30 的值。

So in this very next example here, this is not too much of a leap from what we did before.

是以，在下一個例子中，這與我們之前所做的並沒有太大的區別。

We're still dereferencing this pointer p.

So instead of getting the address, which is what's actually stored in p, what we want to do is get the contents located at that particular address.

是以，我們要做的不是獲取實際存儲在 p 中的地址，而是獲取位於該特定地址的內容。

So we're getting the value of 30, adding it to 5, and then storing it back into the variable location specified by x.

是以，我們得到 30 的值，將其與 5 相加，然後將其存儲回 x 指定的變量位置。

So here we would update that and now have the value of 35 stored at that location.

是以，在這裡我們將對其進行更新，並在該位置存儲 35 的值。

In the very last expression that I have here, I have the dereferencing of the pointer p on both the left-hand side and the right-hand side of the assignment statement.

在最後一個表達式中，我在賦值語句的左側和右側都取消了指針 p 的引用。

Once again, dereferencing this pointer p would just get this value of 35.

同樣，取消引用指針 p 只會得到 35 這個值。

But now when we dereference this pointer p on the left-hand side of the assignment statement, it allows us to store a value at that designated location here.

但現在，當我們在賦值語句的左側取消引用指針 p 時，我們就可以在這裡的指定位置存儲一個值。

So we're designating this particular location here where we want to store a particular value, just like what we had with x.

是以，我們要在這裡指定一個特定的位置來存儲一個特定的值，就像存儲 x 一樣。

So we would have 35 plus 5, which would be 40, and store it at that particular memory location.

是以，我們將 35 加 5，即 40，並將其存儲在特定的內存位置。

So you can see that this dereferencing of this pointer p is serving the exact same purpose as this variable x.

是以可以看出，對指針 p 的取消引用與對變量 x 的取消引用的目的完全相同。

One last example that I wanted to look at is if we made use of the ampersand operator and then did a dereferencing on p.

我想看的最後一個例子是，如果我們使用安培運算符，然後對 p 進行取消引用。

So using what we just discussed, we could say that this dereferencing of p here would just be the same thing as saying x.

是以，根據我們剛才的討論，我們可以說，在這裡對 p 的取消引用與對 x 的引用是一回事。

And if we were to get the address of x, that would just simply be this value of 3.

如果我們要獲取 x 的地址，那麼這個地址就是 3。

But we can also think of this ampersand operator, or excuse me, the address of operator, canceling out the dereferencing operator.

不過，我們也可以把這個括弧運算符，或者不好意思，"地址運算符"（address of operator）看作是取消引用運算符（dereferencing operator）。

So anytime we see these in pairs, we can think of them canceling each other out.

是以，當我們看到它們成對出現時，我們可以認為它們相互抵消了。

So fundamentally, this is just saying see out the address stored there at p, since p is a pointer, which would be 3.

是以，從根本上說，這只是說要找出存儲在 p 處的地址，因為 p 是一個指針，也就是 3。

All right, so in this video so far, we've looked at the concept of a pointer.

好了，在本視頻中，我們已經瞭解了指針的概念。

And we said that a pointer was just simply a data type that points to or references another value in memory via that value's address.

我們說過，指針只是一種通過地址指向或引用內存中另一個值的數據類型。

是以，指針實際上保存的是一個地址。

And we also looked at the address of operator and the contents of, also known as the dereference operator, and how those related to pointers.

我們還研究了地址運算符和內容運算符（也稱為取消引用運算符），以及它們與指針的關係。

But all the examples we saw were rather contrived and aren't really the way that pointers are actually used.

但是，我們看到的所有例子都是臆造出來的，並不是指針的真正用法。

So how are pointers really used in programs?

那麼，程序中究竟如何使用指針呢？

Well, one way is to refer to new memory reserved during program execution.

一種方法是在程序執行過程中引用預留的新內存。

And we'll look at this concept more closely in upcoming videos, because it turns out that anytime that we allocate new memory during program execution, then what was being returned is an actual pointer or an address to that particular memory location.

在接下來的視頻中，我們將更深入地瞭解這一概念，因為事實證明，在程序執行過程中，無論何時分配新內存，返回的都是指向該特定內存位置的實際指針或地址。

So we need to have pointers that hold the address of where that new thing is being allocated in memory.

是以，我們需要有指針來保存新內容在內存中的分配地址。

We can also use pointers to refer and share large data structures without making copies of these structures.

我們還可以使用指針來引用和共享大型數據結構，而無需複製這些結構。

So you can imagine a pointer may be referencing some particular file that you may be reading.

是以，你可以想象一個指針可能會引用你正在讀取的某個特定文件。

And you may not want to make copies of that file, that large data structure.

而且，你可能不想複製那個文件、那個大型數據結構。

But you can just use a pointer to address, to reference that particular thing in memory.

但你可以使用地址指針來引用內存中的特定內容。

And then finally, we can use pointers to specify relationships among data.

最後，我們可以使用指針來指定數據之間的關係。