C++ STL Tutorial
In the previous chapters, we have learned the concept of C++ templates. C++ STL (Standard Template Library) is a set of powerful C++ template classes that provides common template classes and functions. These template classes and functions can implement a variety of popular and commonly used algorithms and data structures, such as vectors, linked lists, and queues. , stack.
The core of the C++ Standard Template Library includes the following three components:
| Component | Description |
|---|---|
| Containers | Containers are used to manage a collection of objects of a certain type. C++ provides various types of containers, such as deque, list, vector, map, etc. |
| Algorithms | Algorithms act on containers. They provide ways to perform a variety of operations, including initializing, sorting, searching, and transforming the contents of the container. |
| Iterators (iterators) | Iterators are used to traverse the elements of an object collection. These collections may be containers or subsets of containers. |
These three components all come with rich predefined functions to help us handle complex tasks in a simple way.
The following program demonstrates a vector container (a C++ standard template), which is very similar to an array. The only difference is that the vector automatically handles its own storage requirements when it needs to be expanded in size:
#include <iostream>
#include <vector>
using namespace std;
int main()
{
// 创建一个向量存储 int
vector<int> vec;
int i;
// 显示 vec 的原始大小
cout << "vector size = " << vec.size() << endl;
// 推入 5 个值到向量中
for(i = 0; i < 5; i++){
vec.push_back(i);
}
// 显示 vec 扩展后的大小
cout << "extended vector size = " << vec.size() << endl;
// 访问向量中的 5 个值
for(i = 0; i < 5; i++){
cout << "value of vec [" << i << "] = " << vec[i] << endl;
}
// 使用迭代器 iterator 访问值
vector<int>::iterator v = vec.begin();
while( v != vec.end()) {
cout << "value of v = " << *v << endl;
v++;
}
return 0;
}When the above code is compiled and executed, it will produce the following results:
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
There are a few things to note about the various functions used in the above example:
push_back( ) member function inserts a value at the end of the vector, extending the vector's size if necessary.
size( ) function displays the size of a vector.
begin( ) function returns an iterator pointing to the beginning of the vector.
end( ) function returns an iterator pointing to the end of the vector.
