stl - 字符串是一个向量？ [英] stl - Is a string a vector?

问题描述

我在一些测验中遇到了一个问题
是字符串是向量吗？如果是，以什么方式？ >
两者都可以随机访问内容。
但是字符串有一些方法向量dosn`t.It也可能有引用计数。
所以显然字符串不是一个向量（typedef字符串向量）
是否有已知的实现 class string：public vector< char> ？

I have encountered a question in some quiz "Is a string a vector? If yes, in what way? If no, why not?" Both of them have random access to the content. But string has some methods which vector dosn`t.It also might have reference count . So it is obvious that string is not exactly a vector (typedef string vector) Are there known implementations in which class string : public vector <char>? If not - what is the reason for not implementing it so?

推荐答案

从纯哲学的角度来看：是的，字符串是向量的类型。它是存储字符的连续内存块（向量是存储任意类型对象的连续内存块）。因此，从这个角度来看，字符串是一种特殊的向量。

From a purely philosophical point of view: yes, a string is a type of vector. It is a contiguous memory block that stores characters (a vector is a contiguous memory block that stores objects of arbitrary types). So, from this perspective, a string is a special kind of vector.

在设计和实现 std :: string 和 std :: vector ，它们共享一些相同的接口元素（例如连续的内存块， operator [] ），但是 std :: string 不会不从 std :: vector （旁注：你不应该公开派生自标准容器，因为它们不是基于类的 - 例如它们没有虚拟析构函数），也不能直接互相转换。也就是说，以下不会编译：

In terms of design and implementation of std::string and std::vector, they share some of the same interface elements (e.g. contiguous memory blocks, operator[]), but std::string does not derive from std::vector (side note: you should not publicly derive from standard containers as they are not designed to be based classes - e.g. they do not have virtual destructors), nor are they directly convertible to each other. That is, the following will not compile:

std::string s = "abc";
std::vector<char> v = s; // ERROR!

但是，由于它们都支持迭代器，因此可以将字符串转换为向量：

However, since they both have iterator support, you can convert a string to a vector:

std::string s = "abc";
std::vector<char> v(s.begin(), s.end()); // note that the vector will NOT include the '\0' character

std :: string 将不再具有引用计数（如C ++ 11）作为许多实现被C ++ 11标准禁止的写时复制功能。

std::string will no longer have a reference count (as of C++11) as the copy-on-write functionality that many implementations used was forbidden by the C++11 standard.

从内存角度来看， std :: string 的实例会看起来非常类似到 std :: vector< char> （例如，它们都将具有指向它们的存储器位置，大小，容量的指针），但是两个类是不同的。

From a memory perspective, an instance of std::string will look very similar to a std::vector<char> (e.g. they both will have a pointer to their memory location, a size, a capacity), but the functionality of the two classes is different.

这篇关于stl - 字符串是一个向量？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！