c++ stl隊列初始化

Here, we have to declare, initialize and access a vector in C++ STL.

在這里，我們必須聲明，初始化和訪問C ++ STL中的向量。

向量聲明 (Vector declaration)

Syntax:

句法：

vector<data_type> vector_name;

Since, vector is just like dynamic array, when we insert elements in it, it automatically resize itself.

由于vector就像動態(tài)數(shù)組一樣，當我們在其中插入元素時，它會自動調整大小。

We can also use, the following syntax to declare dynamic vector i.e a vector without initialization,

我們還可以使用以下語法聲明動態(tài)向量，即不初始化的向量 ，

vector<data_type> vector_name{};

If, we want to initialize a vector with initial elements, we can use following syntax,

如果要使用初始元素初始化向量，則可以使用以下語法，

vector<data_type> vetor_name{elements};

矢量迭代器 (Vector iterator)

To access/iterate elements of a vector, we need an iterator for vector like containers. We can use following syntax to declare a vector iterator:

要訪問/迭代向量的元素，我們需要一個類似容器的向量迭代器。 我們可以使用以下語法來聲明向量迭代器：

vector<data_type>::iterator iterator_name;

Example:

例：

vector<int>::iterator it;

vector :: begin()和vector :: end()函數(shù) (vector:: begin() and vector::end() functions )

Function vector::begin() return an iterator, which points to the first element in the vector and the function vector::end() returns an iterator, which points to the last element in the vector.

函數(shù)vector :: begin()返回一個迭代器，該迭代器指向向量中的第一個元素，函數(shù)vector :: end()返回一個迭代器，該迭代器指向向量中的最后一個元素。

Program 1: Declare vector with Initialization and print the elements

程序1：使用初始化聲明矢量并打印元素

#include <iostream> #include <vector>using namespace std;int main() {// declare vector with 5 elements vector<int> num{10, 20, 30, 40, 50} ;//print the elements - to iterate the elements,//we need an iterator vector<int>::iterator it;//iterate and print the elementscout<< "vector (num) elements: ";for( it=num.begin(); it!=num.end() ; it++ )cout<< *it << " ";return 0; }

Output

輸出量

vector (num) elements: 10 20 30 40 50 .minHeight{min-height: 250px;}@media (min-width: 1025px){.minHeight{min-height: 90px;}} .minHeight{min-height: 250px;}@media (min-width: 1025px){.minHeight{min-height: 90px;}}

Program 2: Declare a vector without initialization, insert some elements and print

程序2：在不初始化的情況下聲明向量，插入一些元素并打印

To insert elements in vector, we use vector::push_back() – this is a predefined function, it insert/pushes the elements at the end of the vector.

要在vector中插入元素，我們使用vector :: push_back() –這是一個預定義的函數(shù)，它將在矢量末尾插入/推送元素。

#include <iostream> #include <vector>using namespace std;int main() {// declare vector vector<int> num{};//insert elementsnum.push_back (100);num.push_back (200);num.push_back (300);num.push_back (400);num.push_back (500);//print the elements - to iterate the elements,//we need an iteratorvector<int>::iterator it;//iterate and print the elementscout<< "vector (num) elements: ";for(it=num.begin (); it !=num.end (); it++ )cout<< *it << " ";return 0; }

Output

輸出量

vector (num) elements: 100 200 300 400 500

翻譯自: https://www.includehelp.com/stl/declare-initialize-and-access-a-vector.aspx

c++ stl隊列初始化

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