Cplusplus 简明教程

C++ STL Tutorial

希望你已经理解了我们之前讨论过的 C 模板概念。C STL(标准模板库) 是一组功能强大的 C++ 模板类，以包含模板的通用类和函数来实现许多流行且常用的算法和数据结构（如向量、列表、队列和栈）。

Hope you have already understood the concept of C Template which we have discussed earlier. The C STL (Standard Template Library) is a powerful set of C++ template classes to provide general-purpose classes and functions with templates that implement many popular and commonly used algorithms and data structures like vectors, lists, queues, and stacks.

C++ 标准模板库的核心包含以下三个结构完善的组件 −

At the core of the C++ Standard Template Library are following three well-structured components −

Sr.No

Component & Description

1

Containers Containers are used to manage collections of objects of a certain kind. There are several different types of containers like deque, list, vector, map etc.

2

Algorithms Algorithms act on containers. They provide the means by which you will perform initialization, sorting, searching, and transforming of the contents of containers.

3

Iterators Iterators are used to step through the elements of collections of objects. These collections may be containers or subsets of containers.

我们将在下一章讨论 C STL 的所有三个组件，同时讨论 C 标准库。现在，请记住所有这三个组件都有一组丰富的预定义函数，这些函数可以帮助我们以非常简单的方式完成复杂的任务。

We will discuss about all the three C STL components in next chapter while discussing C Standard Library. For now, keep in mind that all the three components have a rich set of pre-defined functions which help us in doing complicated tasks in very easy fashion.

让我们看一个用向量容器（C++ 标准模板）编写的程序，该容器类似于数组，但有这样一种例外，如果数组增长，它会自动处理它自己的存储需求 −

Let us take the following program that demonstrates the vector container (a C++ Standard Template) which is similar to an array with an exception that it automatically handles its own storage requirements in case it grows −

#include <iostream>
#include <vector>
using namespace std;

int main() {

   // create a vector to store int
   vector<int> vec;
   int i;

   // display the original size of vec
   cout << "vector size = " << vec.size() << endl;

   // push 5 values into the vector
   for(i = 0; i < 5; i++) {
      vec.push_back(i);
   }

   // display extended size of vec
   cout << "extended vector size = " << vec.size() << endl;

   // access 5 values from the vector
   for(i = 0; i < 5; i++) {
      cout << "value of vec [" << i << "] = " << vec[i] << endl;
   }

   // use iterator to access the values
   vector<int>::iterator v = vec.begin();
   while( v != vec.end()) {
      cout << "value of v = " << *v << endl;
      v++;
   }

   return 0;
}

编译并执行上述代码后，将产生以下结果 −

When the above code is compiled and executed, it produces the following result −

vector size = 0
extended vector size = 5
value of vec [0] = 0
value of vec [1] = 1
value of vec [2] = 2
value of vec [3] = 3
value of vec [4] = 4
value of v = 0
value of v = 1
value of v = 2
value of v = 3
value of v = 4

以下是关于我们在上例中使用的各种函数的一些注意事项 −

Here are following points to be noted related to various functions we used in the above example −

  1. The push_back( ) member function inserts value at the end of the vector, expanding its size as needed.

  2. The size( ) function displays the size of the vector.

  3. The function begin( ) returns an iterator to the start of the vector.

  4. The function end( ) returns an iterator to the end of the vector.