Vector

1.string str[]={"Alex","John","Robert"};

// creates vector with 10 elements,

 // and assign value 0 for each 

vector<int> v3(10,0);

vector<string> v4(str+0,str+3); 

vector<string>::iterator sIt = v4.begin(); 

while ( sIt != v4.end() ) 

cout << *sIt++ << " "; 

cout << endl; 

// copy constructor 

vector<string> v5(v4); 

for ( int i=0; i<3; i++）

cout << v5[i] << " "; 

cout << endl; 

return 0; 

} 

OUTPUT: 

// Alex John Robert 

// Alex John Robert









1、string s1( "Mississippi" ); 

string s3; 　　

// 拷贝s1 的前4 个字符 　　

s3.assign( s1, 0, 4 ); 　　

s3 现在的值为“Miss”。 　　

2、 string str1, str2 = "War and Peace"; 　　

str1.assign( str2, 4, 3 ); 　　

cout << str1 << endl; 　　

显示 　　and





#include <iostream> 

#include <vector> 

using namespace std; 

int main () 

{ 

vector<int> v(3,0); 

v[0] = 100; 

v.at(1) = 200; 

for ( int i=0; i<3; i++ ) 

cout << v.at(i) << " "; 

cout << endl; 

return 0;

 } 

OUTPUT: // 100 200 0





#include <iostream> 

#include <vector> 

#include <iterator>

 #include <numeric> //iota

using namespace std; 

int main () 

{ 

vector<int> v(5); 

iota(v.begin(),v.end(),1);//stl自增函数 

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

while ( It != v.end() )

cout << *It++ << " "; 

cout << endl; 

// third element of the vector 

It = v.begin()+2; 

cout << *It << endl; 

return 0;

} 

OUTPUT: // 1 2 3 4 5 

// 3



 　



1.

#include <iostream>

 #include <vector> 

using namespace std; 

int main () 

{ 

vector<int> v(10); 

cout << "Size of v = " << v.size() << endl; 

cout << "Capacity of v = " << v.capacity() << endl; 

v.resize(100); 

cout << "After resizing:" << endl; 

cout << "Size of v = " << v.size() << endl; 

cout << "Capacity of v = " << v.capacity() << endl; 

return 0;

}

 OUTPUT: // Size of v = 10

 // Capacity of v = 10 

// After resizing: 

// Size of v = 100 

// Capacity of v = 100







2.fill(v.begin(),v.end(),5);



v.clear();//清除vector内容





3.#include <iostream> 

#include <vector> 

using namespace std; 

int main () 

{ 

vector<int> v; 

cout << "Vector is "; 

v.empty() ? cout << "" : cout << "not "; 

cout << "empty" << endl; 

//如c++中的vector头文件里面就有这个push_back函数，在vector类中作用为在vector尾



部加入一个数据。

v.push_back(100); 

cout << "Vector is "; 

v.empty() ? cout << "" : cout << "not "; 

cout << "empty" << endl; return 0; 

}

 // Vector is empty 

// Vector is not empty





4.

#include <iostream> 

#include <vector> 

#include <iterator> 

#include <numeric> 

using namespace std; 

int main () 

{ 

vector<int> v(5);

iota(v.begin(),v.end(),1); 

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

while ( It != v.end() ) 

cout << *It++ << " "; 

cout << endl; 

// last element of the vector 

It = v.end()-1; 

cout << *It << endl; 

return 0; 

} 

OUTPUT: // 1 2 3 4 5 

// 5



5.

#include <vector>

#include <iostream>

using namespace std;



int main(int argc, char* argv[])

{

    vector<int> vect;    

    vect.push_back(1);

    vect.push_back(2);

    vect.push_back(3);

    vect.push_back(4);

    vect.resize(100);    //新的空间不覆盖原有四个元素占有的空间，现在size和



capacity都是100

    cout<<vect.size()<<endl;

    int i = 0;

    for (i = 0; i < 104; i++)

    {

        cout<<vect[i]<<endl;  

    }

    return 0;

}



#include <vector>

#include <iostream>

using namespace std;



int main(int argc, char* argv[])

{

    vector<int> vect;        

    vect.resize(100);    //分配100个空间

        vect.push_back(1);

    vect.push_back(2);

    vect.push_back(3);

    vect.push_back(4);

    cout<<vect.size()<<endl; //现在size和capacity都是104

    int i = 0;

    for (i = 0; i < 104; i++)

    {

        cout<<vect[i]<<endl;  

    }

    return 0;

}





6.

#include <iostream> 

#include <vector> 

using namespace std; 

int main () 

{

 vector<int> v(10); 

cout << "Size of v = " << v.size() << endl; 

cout << "Max_size of v = " << v.max_size() << endl; 

return 0;

 } 

OUTPUT: // Size of v = 10 

// Max_size of v = 1073741823





7.pop_back() 删除最后一个元素



template <class T> 

class Print 

{ public: 

void operator () (T& t) 

{ cout << t << " "; } }; 

//============================= 

int main () 

{ 

vector<int> v; 

Print<int> print; 

for ( int i=0; i<5; i++ )

 v.push_back(i+1); 

while ( !v.empty() ) 

{ 

for_each(v.begin(),v.end(),print);

 cout << endl; 

v.pop_back(); 

} return 0; 

} OUTPUT: // 1 2 3 4 5 

// 1 2 3 4 

// 1 2 3

 // 1 2 

// 1







8.

#include <iostream> 

#include <vector> 

using namespace std; 

int main () 

{ 

vector<int> v(5,0); 

// 5 elements, each - value 0 



/*------------------------------------------------*/ 

cout << "Size of v = " << v.size() << endl; 

cout << "Capacity v = " << v.capacity() << endl;

 cout << "Value of each element is - "; 

for ( int i = 0; i < v.size(); i++ ) 

cout << v[i] << " "; 

cout << endl; 

v[0] = 5; 

// new value for first element 

v[1] = 8; 

v.push_back(3);

 // creates new (6th) element of vector, 

v.push_back(7); // automatically increases size

 cout << endl; // capacity of vector v 

cout << "Size of v = " << v.size() << endl; 

cout << "Capacity v = " << v.capacity() << endl; 

cout << "Value of each element is - "; 

for ( int i = 0; i < v.size(); i++ )

cout << v[i] << " ";

cout << endl << endl; 

v.reserve(100); // increase capacity to 100 

cout << "Size of v1_int = " << v.size() << endl;

 cout << "Capacity v1_int = " << v.capacity() << endl; 

int size = sizeof(v); // how big is vector itself 

cout << "sizeof v = " << size << endl; 

return 0; 

} 



// Size of v = 5 

// Capacity v = 5//返回当前vector在重新进行内存分配以前所能容纳的元素数量。

 // Value of each element is - 0 0 0 0 0 

// 

// Size of v = 7 

// Capacity v = 10 

// Value of each element is - 5 8 0 0 0 3 7 

// 

// Size of v = 7

 // Capacity v = 100

 // sizeof v = 12



9.



#include <iostream> 

#include <vector> 

#include <algorithm> 

#include <iterator> 

using namespace std; 

int main () 

{ 

vector<int> v(5); 

for ( int i=0; i<5; i++ ) 

v[i] = i*2; 

copy(v.begin(),v.end(), ostream_iterator<int>(cout," "));

 cout << endl; 

v.resize(7,100); 

copy(v.begin(),v.end(), ostream_iterator<int>(cout," "));

cout << endl; v.resize(4); 

copy(v.begin(),v.end(), ostream_iterator<int>(cout," "));

 cout << endl; 

return 0; 

}

 OUTPUT: // 0 2 4 6 8 

// 0 2 4 6 8 100 100

 // 0 2 4 6





10.