C tutorial on the Standard Template Library (STL)
STL(标准模板库)是C++标准库的重要组成部分,包含容器、迭代器和算法三大核心组件。1. 容器如vector、map、set用于存储数据;2. 迭代器用于访问容器元素;3. 算法如sort、find用于操作数据。选择容器时,vector适合动态数组,list适合频繁插入删除,deque支持双端快速操作,map/unordered_map用于键值对查找,set/unordered_set用于去重。使用算法时应包含<algorithm>头文件,并配合迭代器和lambda表达式。注意避免失效迭代器、删除时更新迭代器、不可修改map/set的key值,或使用范围for循环提高安全性。掌握STL能显著提升代码效率与可读性。
如果你刚开始学 C++,可能已经听说过 STL 这个词。它全称是 Standard Template Library(标准模板库),是 C++ 中非常强大的一部分,提供了一系列通用的数据结构和算法。这篇文章不会从头讲语法,而是直接带你了解 STL 的核心组成、如何使用常见容器和算法,并给出一些实用建议。

什么是 STL,为什么重要?
STL 是 C++ 标准库的一部分,主要包含三个核心组件:容器(Containers)、迭代器(Iterators) 和 算法(Algorithms)。它们共同作用,让你可以高效地处理数据。

- 容器用来存储数据,比如
vector
、map
、set
。 - 迭代器像指针一样用来访问容器中的元素。
- 算法则是对这些数据进行操作的函数,例如排序、查找等。
用 STL 的好处在于你不用自己实现链表、动态数组这些基础结构,而且代码会更简洁、可读性更高。
常见容器怎么选?看需求
C++ 提供了多种容器类型,每种适用于不同场景。以下是最常用的几个:

-
vector
:动态数组,适合顺序访问,尾部插入/删除快。 -
list
:双向链表,适合频繁在中间插入或删除元素。 -
deque
:双端队列,支持两端快速插入。 -
map
/unordered_map
:键值对集合,前者基于红黑树有序,后者基于哈希无序但更快。 -
set
/unordered_set
:集合类型,用于去重,同理有有序和无序之分。
举个例子,如果你需要一个列表,随时添加元素又不确定大小,首选 vector
;如果要根据关键字快速查找,就用 map
或 unordered_map
。
小提示:尽量避免用
vector<bool>
,这个特化版本行为跟普通 vector 不太一样,容易踩坑。
算法怎么用?别自己造轮子
STL 提供了大量的算法函数,都在 <algorithm>
头文件里。常见的如:
-
sort()
:排序 -
find()
:查找元素 -
copy()
:复制数据 -
transform()
:转换数据
这些函数通常接受两个迭代器作为参数,表示操作范围。例如:
#include <algorithm> #include <vector> std::vector<int> v = {5, 2, 8, 1}; std::sort(v.begin(), v.end()); // 排序后变成 {1, 2, 5, 8}
你可以配合 lambda 表达式来自定义排序规则或者判断条件,这样写出来的代码既简洁又灵活。
注意:有些算法返回的是迭代器而不是索引,使用前记得检查是否合法(比如
find()
找不到时返回end()
)。
使用迭代器时要注意什么?
迭代器是连接容器和算法的桥梁,但在使用过程中有几个地方容易出错:
- 避免使用已经失效的迭代器。例如你在遍历
vector
时进行了扩容操作(比如push_back
),可能会导致迭代器失效。 - 删除元素时注意更新迭代器。例如使用
list.erase(it++)
是一种常见做法。 - 在使用
map
或set
时,不要尝试修改 key 的值,因为这会影响内部结构。
如果你不太确定迭代器的行为,可以用范围 for 循环来简化操作,比如:
for (const auto& item : my_vector) { std::cout << item << std::endl; }
这种方式更直观,也更安全。
基本上就这些。STL 是 C++ 编程中不可或缺的一部分,掌握好常用容器和算法,能让你写出更清晰、高效的代码。虽然一开始可能会觉得有点抽象,但多用几次就能上手了。
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