一.语法:
#include <vector>
vector(); 默认构造函数
vector( const vector& c ); 从一个已知的vector对象复制到新vector对象中
vector( size_type num, const TYPE& val = TYPE() ); 有num个元素,如果有val,则每个元素的值都是val
vector( input_iterator start, input_iterator end ); 被初始化为start到end的元素
~vector(); 析钩函数
例子:
#include <vector>
vector(); 默认构造函数
vector( const vector& c ); 从一个已知的vector对象复制到新vector对象中
vector( size_type num, const TYPE& val = TYPE() ); 有num个元素,如果有val,则每个元素的值都是val
vector( input_iterator start, input_iterator end ); 被初始化为start到end的元素
~vector(); 析钩函数
例子:
// 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;结果:42424242424242424242
v.assign(10,42); 构造函数1
for(int i =0; i < v.size(); i++){
cout << v[i]<<" ";
}
cout << endl;
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);结果:
cout <<"The capacity of v1 is "<< v1.capacity()<< endl;
vector<int> v2;
v2.reserve(20);
cout <<"The capacity of v2 is "<< v2.capacity()<< endl;
The capacity of v1 is10
The capacity of v2 is20
6.clear
#include <vector>
void clear();
清空所有元素
