vector

Introduction(介绍)

This article aims to introduce the std::vector as well as cover some of the most common vector member functions and how to use them properly. The article will also discuss predicates and function pointers as used in common iterator algorithms such as remove_if() and for_each(). After reading this article, the reader should be able to use the vector container effectively and should find no use for dynamic C-style arrays again.

这边文章主旨是介绍std::vector和其常用的成员函数，以及如何使用它们。

Vector Overview

The vector is part of the C++ Standard Template Library (STL); an amalgamation of general-purpose, templatized classes and functions that implement a plethora of common data structures and algorithms. The vector is considered a container class. Like containers in real-life, these containers are objects that are designed to hold other objects. In short, a vector is a dynamic array designed to hold objects of any type, and capable of growing and shrinking as needed.

In order to use vector, you need to include the following header file:

#include <vector>

The vector is part of the std namespace, so you need to qualify the name. This can be accomplished as shown here:

using std::vector;
vector<int> vInts;

or you can fully qualify the name like this:

std::vector<int> vInts;

I do however suggest that you refrain from declaring global namespaces such as:

using namespace std;

This pollutes the global namespace and may cause problems in later implementations. As for the interface to the vector container, I have listed the member functions and operators of vector in the tables below. 

Vector Member Functions(Vector的成员函数)

Function	Description
assign	Erases a vector and copies the specified elements to the empty vector.
at	Returns a reference to the element at a specified location in the vector.
back	Returns a reference to the last element of the vector.
begin	Returns a random-access iterator to the first element in the container.
capacity	Returns the number of elements that the vector could contain without allocating more storage.
clear	Erases the elements of the vector.
empty	Tests if the vector container is empty.
end	Returns a random-access iterator that points just beyond the end of the vector.
erase	Removes an element or a range of elements in a vector from specified positions.
front	Returns a reference to the first element in a vector.
get_allocator	Returns an object to the allocator class used by a vector.
insert	Inserts an element or a number of elements into the vector at a specified position.
max_size	Returns the maximum length of the vector.
pop_back	Deletes the element at the end of the vector.
push_back	Adds an element to the end of the vector.
rbegin	Returns an iterator to the first element in a reversed vector.
rend	Returns an iterator to the end of a reversed vector.
resize	Specifies a new size for a vector.
reserve	Reserves a minimum length of storage for a vector object.
size	Returns the number of elements in the vector.
swap	Exchanges the elements of two vectors.
vector	Constructs a vector of a specific size or with elements of a specific value or with a specific allocator or as a copy of some other vector.

Vector Operators

Operator	Description
operator[]	Returns a reference to the vector element at a specified position.