C++ Vector用法深入剖析

转载地址：http://blog.163.com/chen_dawn/blog/static/112506320109125221959/

C++编程语言中有一种叫做Vector的应用方法，它的作用在实际编程中是非常重要的。在这里我们将会为大家详细介绍一下C++ Vector的相关应用技巧及基本内容，希望能给大家带来一些帮助。

(1)vector< 类型 > 标识符 ;

(2)vector< 类型 > 标识符(最大容量) ；

(3)vector< 类型 > 标识符（最大容量，初始所有值）；

(4) int i[4] = {12,3,4,5};

 
vector< 类型 > vi(i , i+2); //得到i索引值为3以后的值 ；  

(5)vector< vector<int> > //vi 定义2维的容器；记得一定要有空格，不然会报错

vector< int > line   

// 在使用的时候一定要首先将vi个行进行初始化;   

for(int i = 0 ; i < 10 ; i ++)  

{  

line.push_back(i);  

}  

/// 个人认为使用vector定义二维数组很好，因为是长度可以不预先确定。很好。 

(6)C++ Vector排序

vector< int > vi ;   

vi.push_back(1);  
vi.push_back(3);  
vi.push_back(0);  
sort(vi.begin() , vi.end()); /// /小到大  
reverse(vi.begin(),vi.end()) /// 从大道小 

(7)顺序访问

vector < int > vi ;   
for( int i = 0 ; i < 10 ; i ++)  
{  
vi.push_back(i);  
}   
for(int i = 0 ; i < 10 ; i ++) /// 第一种调用方法  
{  
cout <<vi[i] <<" " ;   
}  
for(vector<int>::iterator it = vi.begin() ; 
it !=vi.end() ; it++) ///第二种调用方法  
{  
cout << *it << " " ;  
} 

(8)寻找

vector < int > vi ;   
for( int i = 0 ; i < 10 ; i ++)  
{  
vi.push_back(i);  
}   
vector < int >::interator it = find(vi.begin() , vi.end,3) ;  
cout << *it << endl ; ///返回容器内找到值的位置。 

(9)使用数组对C++ Vector进行初始化

int i[10] ={1,2,3,4,5,6,7,78,8} ;  
///第一种   
vector<int> vi(i+1,i+3); ///从第2个元素到第三个元素  
for(vector <int>::interator it = vi.begin() ; 
it != vi.end() ; it++)  
{  
cout << *it <<" " ;   
} 

(10) 结构体类型

struct temp  
{  
  public :  
  string str ;   
  public :  
  int id ;  
}tmp;

int main()  
{  
vector <temp> t ;   
temp w1 ;   
w1.str = "Hellowor" ;  
w1.id = 1 ;   
t.push_back(t1);  
cout << w1.str << "," <<w1.id <<endl ;   
return 0 ;   
} 

C++ Vector的基本介绍就为大家介绍到这里。

vector::push_back

public member function

void push_back ( const T& x );

Add element at the end

Adds a new element at the end of the vector, after its current last element. The content of this new element is initialized to a copy of  x .

This effectively increases the vector  size  by one, which causes a reallocation of the internal allocated storage if the vector  size  was equal to the vector  capacity before the call. Reallocations invalidate all previously obtained iterators, references and pointers.

Parameters

x

Value to be copied to the new element.
T is the first template parameter (the type of the elements stored in the vector).

Return value

none

If a reallocation happens, it is performed using  Allocator::allocate() , which may throw exceptions (for the default  allocator ,  bad_alloc  is thrown if the allocation request does not succeed).

Example

// vector::push_back
#include <iostream>
#include <vector>

int main ()
{
  std::vector<int> myvector;
  int myint;

  std::cout << "Please enter some integers (enter 0 to end):\n";

  do {
    std::cin >> myint;
    myvector.push_back (myint);
  } while (myint);

  std::cout << "myvector stores " << int(myvector.size()) << " numbers.\n";

  return 0;
}

The example uses  push_back  to add a new element to the vector each time a new integer is read.

Complexity

Constant (amortized time, reallocation may happen).

See also

vector::pop_back

Delete last element (public member function)

vector::insert

Insert elements (public member function)