// create a vector of random integers   创建一个包含随机数的vector对象

 cout <<"original vector: ";

 vector<int> v;

 for(int i =0; i <10; i++){

   int num =(int) rand()%10;

   cout << num <<" ";

   v.push_back( num );

 }

 cout << endl;            


 // find the first element of v that is even   找到vector对象中的第一个元素

 vector<int>::iterator iter1 = v.begin();

 while( iter1 != v.end()&&*iter1 %2!=0){

   iter1++;

 }              


 // find the last element of v that is even   找到最后一个元素

 vector<int>::iterator iter2 = v.end();

 do{

   iter2--;

 }while( iter2 != v.begin()&&*iter2 %2!=0);              


 // only proceed if we find both numbers   找到初始和结束的元素

 if( iter1 != v.end()&& iter2 != v.begin()){

   cout <<"first even number: "<<*iter1 <<", last even number: "<<*iter2 << endl;         


   cout <<"new vector: ";

   vector<int> v2( iter1, iter2 );

   for(int i =0; i < v2.size(); i++){

     cout << v2[i]<<" ";

   }

   cout << endl;

 }

结果:

original vector:1979272198

 first even number:2, last even number:8

 new vector:27219     


二:方法


1.assign

#include <vector>

void assign( size_type num, const TYPE& val );

void assign( input_iterator start, input_iterator end );

例子:
vector<int> v;

 v.assign(10,42); 构造函数1

 for(int i =0; i < v.size(); i++){

   cout << v[i]<<" ";

 }

 cout << endl;            
结果:42424242424242424242
vector<int> v1;

 for(int i =0; i <10; i++){

   v1.push_back( i );

 }              


 vector<int> v2;

 v2.assign( v1.begin(), v1.end());   构造函数2          


 for(int i =0; i < v2.size(); i++){

   cout << v2[i]<<" ";

 }

 cout << endl;            

结果：0123456789


2.at





#include <vector>
TYPE& at( size_type loc );

const TYPE& at( size_type loc ) const;

例子:

vector<int> v(5,1);

 for(int i =0; i <10; i++){

   cout <<"Element "<< i <<" is "<< v[i]<< endl;

 }   


下面的安全些:

vector<int> v(5,1);

 for(int i =0; i <10; i++){

   cout <<"Element "<< i <<" is "<< v.at(i)<< endl;

 }

    


3.back

#include <vector>
TYPE& back();

const TYPE& back() const;


例子:

vector<int> v;

 for(int i =0; i <5; i++){

   v.push_back(i);

 }

 cout <<"The first element is "<< v.front()

      <<" and the last element is "<< v.back()<< endl;     

结果:

The first element is0and the last element is4     



4.begin

#include <vector>

iterator begin();

const_iterator begin() const;

例子:

vector<string> words;

  string str;

  

  while( cin >> str ) words.push_back(str);


  vector<string>::iterator iter;

  for( iter = words.begin(); iter != words.end(); iter++){

    cout <<*iter << endl;

  }

结果：

输入:hey mickey you're so fine








输出:hey 

  mickey 

  you're 

  so 

  fine

5.capacity

#include <vector>
size_type capacity() const;

例子:
vector<int> v1(10);

 cout <<"The capacity of v1 is "<< v1.capacity()<< endl;

 vector<int> v2;

 v2.reserve(20);

 cout <<"The capacity of v2 is "<< v2.capacity()<< endl;         
结果:

The capacity of v1 is10

 The capacity of v2 is20 

6.clear

#include <vector>

void clear();

清空所有元素