vector 内部方法大全学习（初学者的参考资料）

1 vector构造函数：也就是如何对一个vector对象进行初始化
////////////////////////////代码//////////////////////////////////////
explicit vector ( const Allocator& = Allocator() );
explicit vector ( size_type n, const T& value= T(), const Allocator& = Allocator() );
template <class InputIterator>

　　vector ( InputIterator first, InputIterator last, const Allocator& = Allocator() );
vector ( const vector<T,Allocator>& x );
////////////////////////////代码//////////////////////////////////////
参数解释：n---初始化元素个数

　　　　　T---你所要添加进去的元素
　　　　　first---容器第一个元素

　　　　 last---容器最后一个元素

　　　　　x---vector的一个引用
示例：
// constructing vectors
#include <iostream>
#include <vector>
using namespace std;

int main ()
{
unsigned int i;

// constructors used in the same order as described above:
vector<int> first;            // 初始化一个int类型的空vector变量
vector<int> second (4,100);             // 初始化4个100
vector<int> third (second.begin(),second.end());
// 通过second 进行赋值
vector<int> fourth (third);               // a copy of third

// the iterator constructor can also be used to construct from arrays:
int myints[] = {16,2,77,29};
vector<int> fifth (myints, myints + sizeof(myints) / sizeof(int) );

cout << "The contents of fifth are:";
for (i=0; i < fifth.size(); i++)
    cout << " " << fifth[i];

cout << endl;
return 0;
}
输出结果：
The contents of fifth are: 16 2 77 29

2 vector::~vector 析构函数
调用每一个元素对象的析构函数

下面是成员函数
3 vector::assign
template <class InputIterator>
void assign ( InputIterator first, InputIterator last );

void assign ( size_type n, const T& u );

如　c.assign(beg,end) //将[beg; end)区间中的数据赋值给c

　　c.assign(n,elem)     //将n个elem的拷贝赋值给c

示例：
// vector assign
#include <iostream>
#include <vector>
using namespace std;

int main ()
{
vector<int> first;
vector<int> second;
vector<int> third;

first.assign (7,100);             // a repetition 7 times of value 100

vector<int>::iterator it;
it=first.begin()+1;

second.assign (it,first.end()-1); // the 5 central values of first

int myints[] = {1776,7,4};
third.assign (myints,myints+3);   // assigning from array.

cout << "Size of first: " << int (first.size()) << endl;
cout << "Size of second: " << int (second.size()) << endl;
cout << "Size of third: " << int (third.size()) << endl;
return 0;
}
输出结果
Size of first: 7
Size of second: 5
Size of third: 3

4   vector::at
const_reference at ( size_type n ) const;
reference at ( size_type n ); ---返回 vector 内的第n个值，相当于数组下标，从0开始

代码示例
// vec.cpp : Defines the entry point for the console application.
#include "stdafx.h"
#include <iostream>
#include <vector>
using namespace std;

int main ()
{
    vector<int> myvector(10);//初始化10个为0的元素。
    unsigned int i;
    for (i = 0; i < myvector.size(); i ++)
    {
        myvector.at(i)=i;
    }
    cout << "myvector contains:";
    for (i=0; i<myvector.size(); i++)
        cout << " " << myvector.at(i);

    cout << endl;
    return 0;
}

5   vector::back
//返回最后一个元素，而不检查该元素是否存在

Returns a reference to the last element of the vector.

reference back( );
const_reference back( ) const;

Return Value

The last element of the vector. If the vector is empty, the return value is undefined.

Remarks

If the return value of back is assigned to a const_reference, the vector object cannot be modified. If the return value of back is assigned to a reference, the vector object can be modified.

Example

// vector_back.cpp
// compile with: /EHsc
#include <vector>
#include <iostream>

int main( )
{
   using namespace std;   
   vector <int> v1;
   
   v1.push_back( 10 );
   v1.push_back( 11 );

   int& i = v1.back( );
   const int& ii = v1.front( );

   cout << "The last integer of v1 is " << i << endl;
   i--;
   cout << "The next-to-last integer of v1 is "<< ii << endl;
}

Output

The last integer of v1 is 11
The next-to-last integer of v1 is 10

6 vector::begin
iterator begin ();
const_iterator begin () const;

示例
// vector::begin
#include <iostream>
#include <vector>
using namespace std;

int main ()
{
vector<int> myvector;
for (int i=1; i<=5; i++)

　　myvector.push_back(i);

vector<int>::iterator it;
cout << "myvector contains:";
for ( it=myvector.begin() ; it < myvector.end(); it++ )
    cout << " " << *it;

cout << endl;
return 0;
}
输出:
myvector contains: 1 2 3 4 5

7 vector::capacity
返回vector对象存储空间大小

例子：
// comparing size, capacity and max_size
#include <iostream>
#include <vector>
using namespace std;

int main ()
{
vector<int> myvector;

// set some content in the vector:
for (int i=0; i<100; i++)

　　myvector.push_back(i);

cout << "size: " << (int) myvector.size() << " ";
cout << "capacity: " << (int) myvector.capacity() << " ";
cout << "max_size: " << (int) myvector.max_size() << " ";
return 0;
}
A possible output for this program could be:
size: 100
capacity: 141
max_size: 1073741823

8   vector::clear
清除对象内的所有元素，就是调用了析构函数，清空，然后为0

示例
// clearing vectors
#include <iostream>
#include <vector>
using namespace std;

int main ()
{
unsigned int i;
vector<int> myvector;
myvector.push_back (100);
myvector.push_back (200);
myvector.push_back (300);

cout << "myvector contains:";
for (i=0; i<myvector.size(); i++) cout << " " << myvector[i];

myvector.clear();
myvector.push_back (1101);
myvector.push_back (2202);

cout << " myvector contains:";
for (i=0; i<myvector.size(); i++) cout << " " << myvector[i];

cout << endl;

return 0;
}
8   vector::empty
bool empty () const; 判断vector对象时否为空。
示例：
// vector::empty
#include <iostream>
#include <vector>
using namespace std;

int main ()
{
vector<int> myvector;
int sum (0);

for (int i=1;i<=10;i++) myvector.push_back(i);

while (!myvector.empty())
{
     sum += myvector.back();
     myvector.pop_back();
}

cout << "total: " << sum << endl;

return 0;
}
9   vector::end
iterator end ();
const_iterator end () const;

Returns an iterator referring to the past-the-end element in the vector container.
Both iterator and const_iterator are member types. In the vector class template, these are random access iterators

// test_vector.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include <vector>
#include <iostream>
using namespace std;

int _tmain(int argc, _TCHAR* argv[])
{
    vector<int> myvec;
    for (int i=0;i<6;i++)
    {
        myvec.insert(myvec.end(),i);
    }
    cout<<"element";
    vector<int>::iterator it;
    for (it=myvec.begin();it<myvec.end();it++)
    {
        cout<<" "<<(*it)<<endl;
    }
    return 0;
}

10 vector::erase

iterator erase ( iterator position );
iterator erase ( iterator first, iterator last );

删除vector对象里的一个元素或者一个范围内的元素([first,last)).

示例：
// erasing from vector
#include <iostream>
#include <vector>
using namespace std;

int main ()
{
unsigned int i;
vector<unsigned int> myvector;

// set some values (from 1 to 10)
for (i=1; i<=10; i++) myvector.push_back(i);

// erase the 6th element
myvector.erase (myvector.begin()+5);

// erase the first 3 elements:
myvector.erase (myvector.begin(),myvector.begin()+3);

cout << "myvector contains:";
for (i=0; i<myvector.size(); i++)
    cout << " " << myvector[i];
cout << endl;

return 0;
}
Output:
myvector contains: 4 5 7 8 9 10

11 vector::front

reference front ( );
const_reference front ( ) const;

Returns a reference to the first element in the vector container.

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

int main ()
{
vector<int> myvector;

myvector.push_back(78);
myvector.push_back(16);

// now front equals 78, and back 16

myvector.front() -= myvector.back();

cout << "myvector.front() is now " << myvector.front() << endl;

return 0;
}

Output:
myvector.front() is now 62
12 vector::get_allocator
allocator_type get_allocator() const;
// test_vector.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include <vector>
#include <iostream>
using namespace std;

int _tmain(int argc, _TCHAR* argv[])
{
    vector<int> myvector;
    int* p;
    unsigned int i;

    p=myvector.get_allocator().allocate(5);
    for (int i=0;i<5;i++)
    {
        p[i]=i;
    }
    cout << "The allocated array contains:";
    for (i=0; i<5; i++) cout << " " << p[i];
    cout << endl;
    myvector.get_allocator().deallocate(p,5);

    return 0;
}
The allocated array contains: 0 1 2 3 4

13 vector::insert
iterator insert ( iterator position, const T& x );
    void insert ( iterator position, size_type n, const T& x );
template <class InputIterator>
void insert ( iterator position, InputI last );
// test_vector.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include <vector>
#include <iostream>
using namespace std;

int _tmain(int argc, _TCHAR* argv[])
{
    vector<int> myvector(3,100);
    vector<int> ::iterator it;
    it=myvector.begin();
    it=myvector.insert(it,200);
    myvector.insert(it,2,300);

    it=myvector.begin();

    vector<int> anothervector(2,400);
    myvector.insert(it+2,anothervector.begin(),anothervector.end());


    int array[]={501,502,503};
    myvector.insert(myvector.begin(),array,array+3);

    cout << "myvector contains:";

    for (vector<int>::iterator it=myvector.begin();it<myvector.end();it++)
    {
        cout<<" "<<*it;
    }

    return 0;

}

Output:
myvector contains: 501 502 503 300 300 400 400 200 100 100 100
14 vector::max_size
size_type max_size () const;

返回改容器能持有的最大元素数，看一下例子，查看区别

// comparing size, capacity and max_size
#include <iostream>
#include <vector>
using namespace std;

int main ()
{
vector<int> myvector;

// set some content in the vector:
for (int i=0; i<100; i++) myvector.push_back(i);

cout << "size: " << myvector.size() << " ";
cout << "capacity: " << myvector.capacity() << " ";
cout << "max_size: " << myvector.max_size() << " ";
return 0;
}
A possible output for this program could be:
size: 100
capacity: 141
max_size: 1073741823
15 vector::operator=

vector<T,Allocator>& operator= (const vector<T,Allocator>& x);

重载“=”操作符

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

int main ()
{
vector<int> first (3,0);
vector<int> second (5,0);

second=first;
first=vector<int>();

cout << "Size of first: " << int (first.size()) << endl;
cout << "Size of second: " << int (second.size()) << endl;
return 0;
}
输出结果：
Size of first: 0
Size of second: 3

16 vector::operator[]
reference operator[] ( size_type n );
const_reference operator[] ( size_type n ) const;

Returns a reference to the element at position n in the vector container.
返回vector容器内位置为n的元素的引用
和at（）函数相同的功能，就是at（）不在范围内会抛异常
示例
// test_vector.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include <vector>
#include <iostream>
using namespace std;

int _tmain(int argc, _TCHAR* argv[])
{
    vector<int> myvector(10);
    unsigned int i;
    vector<int> ::size_type size=myvector.size();
    for (i=0;i<10;i++)
    {
        myvector[i]=i;
    }
    for (i=0;i<size/2;i++)
    {
        int temp=myvector[size-1-i];
        myvector[size-1-i]=myvector[i];
        myvector[i]=temp;
    }
    for (i=0;i<10;i++)
    {
        cout<<" "<<myvector[i];
    }
    cout<<endl;
    return 0;
}

Output:
myvector contains: 9 8 7 6 5 4 3 2 1 0
17 vector::pop_back
void pop_back ( );

移出元素
示例
// vector::pop_back
#include <iostream>
#include <vector>
using namespace std;

int main ()
{
vector<int> myvector;
int sum (0);
myvector.push_back (100);
myvector.push_back (200);
myvector.push_back (300);

while (!myvector.empty())
{
    sum+=myvector.back();
    myvector.pop_back();
}

cout << "The elements of myvector summed " << sum << endl;

return 0;
}
输出结果：The elements of myvector summed 600
18 vector::push_back
void push_back ( const T& x );

在末尾处添加一个元素
// vector::push_back
#include <iostream>
#include <vector>
using namespace std;

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

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

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

cout << "myvector stores " << (int) myvector.size() << " numbers. ";

return 0;
}
19 vector::rbegin

reverse_iterator rbegin();
const_reverse_iterator rbegin() const;

按照反序迭代输出
示例

// test_vector.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include <vector>
#include <iostream>
using namespace std;

int _tmain(int argc, _TCHAR* argv[])
{
    vector<int> myvector(10);
    unsigned int i;
    vector<int> ::size_type size=myvector.size();
    for (i=0;i<10;i++)
    {
        myvector[i]=i;
    }
    vector<int>::reverse_iterator it;
    for (it=myvector.rbegin();it<myvector.rend();it ++)
    {
        cout<<" "<<*it;
    }
    cout<<endl;
    return 0;
}

输出结果：9 8 7 6 5 4 3 2 1 0

20 vector::rend
public member function
      reverse_iterator rend();
const_reverse_iterator rend() const;

代码同上

21 vector::reserve
void reserve ( size_type n );
Request a change in capacity
Requests that the capacity of the allocated storage space for the elements of the vector container be at least enough to hold n elements.

示例
// vector::reserve
#include <iostream>
#include <fstream>
#include <vector>
using namespace std;

int main ()
{
vector<int> content;
size_t filesize;

ifstream file ("test.bin",ios::in|ios::ate|ios::binary);
if (file.is_open())
{
    filesize=file.tellg();

    content.reserve(filesize);

    file.seekg(0);
    while (!file.eof())
    {
      content.push_back( file.get() );
    }

    // print out content:
    vector<int>::iterator it;
    for (it=content.begin() ; it<content.end() ; it++)
      cout << hex << *it;
}

return 0;
}

22 vector::resize

void resize ( size_type sz, T c = T() );

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

int main ()
{
vector<int> myvector;

unsigned int i;

// set some initial content:
for (i=1;i<10;i++) myvector.push_back(i);

myvector.resize(5);
myvector.resize(8,100);
myvector.resize(12);

cout << "myvector contains:";
for (i=0;i<myvector.size();i++)
    cout << " " << myvector[i];

cout << endl;

return 0;
}
myvector contains: 1 2 3 4 5 100 100 100 0 0 0 0

23 vector::size
size_type size() const;
返回元素个数

示例：
// vector::size
#include <iostream>
#include <vector>
using namespace std;

int main ()
{
vector<int> myints;
cout << "0. size: " << (int) myints.size() << endl;

for (int i=0; i<10; i++) myints.push_back(i);
cout << "1. size: " << (int) myints.size() << endl;

myints.insert (myints.end(),10,100);
cout << "2. size: " << (int) myints.size() << endl;

myints.pop_back();
cout << "3. size: " << (int) myints.size() << endl;

return 0;
}

Output:
0. size: 0
1. size: 10
2. size: 20
3. size: 19
24 vector::swap
交换vector对象里的数据
// swap vectors
#include <iostream>
#include <vector>
using namespace std;

main ()
{
unsigned int i;
vector<int> first (3,100);   // three ints with a value of 100
vector<int> second (5,200); // five ints with a value of 200

first.swap(second);

cout << "first contains:";
for (i=0; i<first.size(); i++) cout << " " << first[i];

cout << " second contains:";
for (i=0; i<second.size(); i++) cout << " " << second[i];

cout << endl;

return 0;
Output:
first contains: 200 200 200 200 200
second contains: 100 100 100

参考链接：http://msdn.microsoft.com/en-us/library/7df54s3x(v=vs.71).aspx

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原文地址：https://www.cnblogs.com/followyourdream/p/3292086.html

vector 内部方法大全 学习（初学者的参考资料）

Return Value

Remarks

Example

Output

vector 内部方法大全学习（初学者的参考资料）