“ptr = ptr -> next” 这个“->”是什么意思？(C++)
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"ptr = ptr - > next" What does this "->" mean? (C++)
提问by Robolisk
Possible Duplicate:
What can I use instead of the arrow operator,->?
What does -> mean in C++?
So I'm currently studying for a C++ exam about Data Structure and Algorithm Development. While looking though my teacher powerpoints, I've noticed that he's used this "->" a lot. And I'm not sure what it means? Is it really a command you can do in c++?
所以我目前正在学习关于数据结构和算法开发的 C++ 考试。在查看我老师的幻灯片时，我注意到他经常使用“->”。我不确定这意味着什么？它真的是你可以在 C++ 中执行的命令吗？
Example 1
示例 1
addrInfo *ptr = head;
while (ptr->next != NULL)
{
ptr = ptr->next;
}
// at this point, ptr points to the last item
Example 2
示例 2
if( head == NULL )
{
head = block;
block->next = NULL;
}
回答by Gordon Bailey
It is a combination dereference and member-access. This ptr->nextis equivalent to (*ptr).next.
它是取消引用和成员访问的组合。这ptr->next相当于(*ptr).next.
回答by Wes Hardaker
The ->operator deferences a pointer and retrieves from it the memory index beyond that point indicated by the following name. Thus:
所述->操作者deferences一个指针和检索从它的存储器索引超出由下列名称表示了这一点。因此：
struct foo {
int bar;
int baz;
};
struct foo something;
struct foo *ptr = &something;
ptr->bar = 5;
ptr->baz = 10;
In the above, the ptrvalue will be the memory location of the somethingstructure (that's what the &does: finds the memory location of something). Then the ptrvariable is later "dereferenced" by the ->operator so that the ptr->barmemory location (an int) is set to 5 and ptr->bazis set to 10.
在上面，ptr值将是something结构的内存位置（这就是它的&作用：找到 的内存位置something）。然后该ptr变量稍后由->操作员“取消引用”，以便将ptr->bar内存位置（一个 int）设置为 5 并ptr->baz设置为 10。
回答by rob05c
The ->operator is specifically a structure dereference. In block->nextit is calling the member variable nextof the object which the pointer blockpoints to. See thispage for a list of member and pointer operators in C++.
的->操作者具体为结构解除引用。在block->next它调用next指针block指向的对象的成员变量。有关C++ 中成员和指针运算符的列表，请参阅此页面。
Basically, it's doing the same thing as block.next, were blockan object rather than a pointer.
基本上，它的作用与block.next, 是block一个对象而不是一个指针。
回答by Timothy Ye
-> is an operator of pointer. It is used for pointer to access member.
-> 是指针的运算符。它用于访问成员的指针。
If you take a look at the defination of "addrInfo", you can find the member "next".
如果查看“addrInfo”的定义，可以找到成员“next”。
Otherwise, you can see the following example:
否则，您可以看到以下示例：
struct student
{
int num;
}
struct student stu;
struct student *p;
p=&stu;
These three operations are equal: 1. stu.num 2. (*P).num 3. p->num
这三个操作是相等的： 1. stu.num 2. (*P).num 3. p->num
回答by D Stanley
It's de-referencing the pointer. It means "Give me the value of the thing pointed at the address stored at ptr". In this example, ptris pointing to a list item so ptr->nextreturns the value of the object's nextproperty.
它正在取消引用指针。它的意思是“给我指向存储在地址的东西的价值ptr”。在本例中，ptr指向一个列表项，因此ptr->next返回对象next属性的值。
