什么 - >是什么意思在C ++？ [英] What does -> mean in C++?

问题描述

可能的重复项：



什么是C ++中的箭头运算符（ - >）同义词？

- > 在C ++中意味着什么？

>感谢：）

解决方案

它是通过指针访问对象的成员函数或成员变量

例如：对于常规变量或引用，使用。运算符以访问成员函数或成员变量。

  std :: string s =abc 
 std :: cout<< s.length（）<< std :: endl; 
  

但是如果你使用指针，你需要使用 - > 运算符：

  std :: string * s = new std :: string abc）; 
 std :: cout<< s  - > length（） std :: endl; 
  

它也可以重载为某个对象类型执行特定的函数。像 shared_ptr 和 unique_ptr 这样的智能指针以及STL容器迭代器重载这个操作符来模仿本地指针语义。 / p>

例如：

  std :: map< int，int& :: iterator it = mymap.begin（），end = mymap.end（）; 
 for（; it！= end; ++ it）
 std :: cout<第一<< std :: endl; 
  

Possible Duplicates:
What is the difference between the dot (.) operator and -> in C++?
What is the arrow operator (->) synonym for in C++?

The header says it all.

What does -> mean in C++?

Thanks :)

解决方案

It's to access a member function or member variable of an object through a pointer, as opposed to a regular variable or reference.

For example: with a regular variable or reference, you use the . operator to access member functions or member variables.

std::string s = "abc";
std::cout << s.length() << std::endl;

But if you're working with a pointer, you need to use the -> operator:

std::string* s = new std::string("abc");
std::cout << s->length() << std::endl;

It can also be overloaded to perform a specific function for a certain object type. Smart pointers like shared_ptr and unique_ptr, as well as STL container iterators, overload this operator to mimic native pointer semantics.

For example:

std::map<int, int>::iterator it = mymap.begin(), end = mymap.end();
for (; it != end; ++it)
    std::cout << it->first << std::endl;

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