std::vector

成員函數

//函數簽名
//default (1)
//explicit vector(const allocator_type& alloc = allocator_type());
//fill(2)
//vector(size_type n, const value_type& val,
//  const allocator_type& alloc = allocator_type());
//range(3)
//template <class InputIterator>
//vector(InputIterator first, InputIterator last,
//  const allocator_type& alloc = allocator_type());
//copy(4)
//vector(const vector& x);
//vector(const vector& x, const allocator_type& alloc);
//move(5)
//vector(vector&& x);
//vector(vector&& x, const allocator_type& alloc);
//initializer list(6)
//vector(initializer_list<value_type> il,
//  const allocator_type& alloc = allocator_type());
#include<iostream>
#include<vector>
using namespace std;
int main()
{
    vector<int> first_vector;
    vector<int> second_vector(4, 100);
    vector<int> third_vector(second_vector.begin(), second_vector.end());
    vector<int> fourth_vector(third_vector);

    int array[] = { 0,8,11 };
    vector<int> my_vector(array, array + sizeof(array) / sizeof(int));

    for each (auto var in my_vector)
    {
        cout << var << " ";
    }
    cout << endl;
    return 0;
}

輸出：
0 8 11

//函數簽名  
//copy(1)  
//vector& operator= (const vector& x);  
//move(2)  
//vector& operator= (vector&& x);  
//initializer list(3)  
//vector& operator= (initializer_list<value_type> il);  
#include<iostream>  
#include<vector>  
using namespace std;  
int main()  
{  
    vector<int> first_vector(8, 0);  
    vector<int> second_vector(11,0);  

    second_vector = first_vector;  
    first_vector = vector<int>();  

    cout << first_vector.size() << endl;  
    cout << second_vector.size() << endl;  
    return 0;  
}  

輸出：
0
8

Iterators

//函數簽名  
//iterator begin() noexcept;  
//const_iterator begin() const noexcept;  
//iterator end() noexcept;  
//const_iterator end() const noexcept;  
//reverse_iterator rbegin();  
//const_reverse_iterator rbegin() const;  
//const_iterator cbegin() const noexcept;  
//const_iterator cend() const noexcept;  
//const_reverse_iterator crbegin() const noexcept;  
//const_reverse_iterator crend() const noexcept;  
#include<iostream>  
#include<vector>  
using namespace std;  
int main()  
{  
    vector<int> my_vector = { 0,8,11 };  

    for (vector<int>::iterator it = my_vector.begin(); it != my_vector.end(); it++)  
        cout << *it << " " ;  
    cout << endl;  

    for (vector<int>::reverse_iterator it = my_vector.rbegin(); it != my_vector.rend(); it++)  
        cout << *it << " ";  
    cout << endl;  

    for (vector<int>::const_iterator it = my_vector.cbegin(); it != my_vector.cend(); it++)  
        cout << *it << " ";  
    cout << endl;  

    for (vector<int>::const_reverse_iterator it = my_vector.crbegin(); it != my_vector.crend(); it++)  
        cout << *it << " ";  
    cout << endl;  

    return 0;  
}  

輸出：
0 8 11
11 8 0
0 8 11
11 8 0

Capacity

//函數簽名  
//size_type size() const;  
//size_type max_size() const;  
//size_type capacity() const;  
//void resize(size_type n, value_type val = value_type());  
//bool empty() const;  
#include<iostream>  
#include<vector>  
using namespace std;  
int main()  
{  
    vector<int> my_vector;  

    for (int i = 1; i <= 100; i++)  
        my_vector.push_back(i);  

    cout << my_vector.size() << endl;  
    //vector增長方式取決去STL的實現，絕大多數STL實現都是以成倍的方式增長，但標準並沒規定  
    cout << my_vector.capacity() << endl;     
    //max_size取決於STL的實現  
    cout << my_vector.max_size() << endl;  

    //多餘的直接拋棄  
    my_vector.resize(3);  
    for each (auto var in my_vector)  
    {  
        cout << var << " ";  
    }  
    cout << endl;  

    //不夠的直接用第二個參數補齊  
    my_vector.resize(5, 1);  
    for each (auto var in my_vector)  
    {  
        cout << var << " ";  
    }  
    cout << endl;  

    //若不夠並且沒有第二個參數，則用0補齊  
    my_vector.resize(7);  
    for each (auto var in my_vector)  
    {  
        cout << var << " ";  
    }  
    cout << endl;  

    if (my_vector.empty())  
        cout << "empty vector" << endl;  
    else  
        cout << "not empty vector" << endl;  

    return 0;  
}  

輸出：
100
141
1073741823
1 2 3
1 2 3 1 1
1 2 3 1 1 0 0
not empty vector

//函數簽名  
//void reserve (size_type n);  
#include<iostream>  
#include<vector>  
using namespace std;
int main()
{
    //我使用的是VS2015   
    //vector增長方式是：1 2 3 4 6 9 13 19 28 42 63 94 141（與絕大多數以2的指數增長實現不一樣）  
    vector<int> first_vector;
    for (int i = 0; i != 100; i++)
        first_vector.push_back(i);
    cout << first_vector.capacity() << endl;

    //如果事先知道vector要放多少個元素，則可以使用reserve()節省空間  
    vector<int> second_vector;
    second_vector.reserve(100);
    for (int i = 0; i != 100; i++)
        second_vector.push_back(i);
    cout << second_vector.capacity() << endl;
    return 0;
}

輸出：
141
100

//函數簽名  
//void shrink_to_fit();  
#include<iostream>  
#include<vector>  
using namespace std;  
int main()  
{  
    vector<int> my_vector;  
    for (int i = 0; i != 6; i++)  
        my_vector.push_back(i);  
    cout << my_vector.size() << endl;  
    cout << my_vector.capacity() << endl;  

    my_vector.resize(4);  
    cout << my_vector.size() << endl;  
    cout << my_vector.capacity() << endl;  

    //注意使用resize()並沒有釋放空間，必須使用  
    my_vector.shrink_to_fit();  
    cout << my_vector.size() << endl;  
    cout << my_vector.capacity() << endl;  
    return 0;  
}  

輸出：
6
6
4
6
4
4

Element access

//函數簽名  
//reference operator[] (size_type n);  
//const_reference operator[] (size_type n) const;  
//reference at(size_type n);  
//const_reference at(size_type n) const;  
//reference front();  
//const_reference front() const;  
//reference back();  
//const_reference back() const;  
//value_type* data() noexcept;  
//const value_type* data() const noexcept;  
#include<iostream>  
#include<vector>  
using namespace std;  
int main()  
{  
    vector<int> my_vector(10);  
    for (int i = 0; i != 10; i++)  
        my_vector[i] = i;  

    for (int i = 0; i != 10; i++)  
        cout << my_vector.at(i) << " ";  
    cout << endl;  

    cout << my_vector.front() << endl;  
    cout << my_vector.back() << endl;  
    return 0;  
}  

輸出：
0 1 2 3 4 5 6 7 8 9
0
9

//函數簽名  
//value_type* data() noexcept;  
//const value_type* data() const noexcept;  
#include<iostream>  
#include<vector>  
using namespace std;  
int main()  
{  
    vector<int> my_vector(5);  
    //返回一個指向數據的指針，類似一個指向數組的指針  
    int *p = my_vector.data();  

    *p = 1;  
    p++;  
    *p = 2;  
    //相當於p現在指向的位置+2  
    p[2] = 3;  
    for (int i = 0; i != 5; i++)  
        cout << my_vector[i] << " ";  
    cout << endl;  
    return 0;  
}  

輸出：
1 2 0 3 0

Modifiers

//函數簽名  
//range(1)  
//template <class InputIterator>  
//void assign(InputIterator first, InputIterator last);  
//fill(2)  
//void assign(size_type n, const value_type& val);  
//initializer list(3)  
//void assign(initializer_list<value_type> il);  
#include<iostream>  
#include<vector>  
using namespace std;  
int main()  
{  
    vector<int> first_vector;  
    vector<int> second_vector;  
    vector<int> third_vector;  

    //5個100  
    first_vector.assign(5, 100);  
    auto it = first_vector.begin() + 1;  

    second_vector.assign(it, first_vector.end() - 1);  

    int ints[] = { 0,8,11 };  
    third_vector.assign(ints, ints + 3);  

    for each (auto var in first_vector)  
    {  
        cout << var << " ";  
    }  
    cout << endl;  
    for each (auto var in second_vector)  
    {  
        cout << var << " ";  
    }  
    cout << endl;  
    for each (auto var in third_vector)  
    {  
        cout << var << " ";  
    }  
    cout << endl;  
    return 0;  
}  

輸出：
100 100 100 100 100
100 100 100
0 8 11

//函數簽名  
//void push_back(const value_type& val);  
//void push_back(value_type&& val);  
//void pop_back();  
//single element(1)  
//iterator insert(const_iterator position, const value_type& val);  
//fill(2)  
//iterator insert(const_iterator position, size_type n, const value_type& val);  
//range(3)  
//template <class InputIterator>  
//iterator insert(const_iterator position, InputIterator first, InputIterator last);  
//move(4)  
//iterator insert(const_iterator position, value_type&& val);  
//initializer list(5)  
//iterator insert(const_iterator position, initializer_list<value_type> il);  
#include<iostream>  
#include<vector>  
using namespace std;  
int main()  
{  
    vector<int> first_vector;  
    first_vector.push_back(1);  
    first_vector.push_back(2);  
    auto it = first_vector.begin() + 1;  
    first_vector.insert(it, 3);  

    for each (auto var in first_vector)  
    {  
        cout << var << " ";  
    }  
    cout << endl;  

    vector<int> second_vector(3, 100);  
    //注意這裏要重新讓迭代器指向一個位置，因爲插入之後會使迭代器失效  
    it = second_vector.begin()+2;  
    second_vector.insert(it,first_vector.begin()+1,first_vector.end());  

    for each (auto var in second_vector)  
    {  
        cout << var << " ";  
    }  
    cout << endl;  

    int myints[] = { 6,6,6 };  
    second_vector.insert(second_vector.begin(),myints, myints + 3);  
    for each (auto var in second_vector)  
    {  
        cout << var << " ";  
    }  
    cout << endl;  

    second_vector.pop_back();  
    for each (auto var in second_vector)  
    {  
        cout << var << " ";  
    }  
    cout << endl;  
    return 0;  
}  

輸出：
1 3 2
100 100 3 2 100
6 6 6 100 100 3 2 100
6 6 6 100 100 3 2

//函數簽名  
//iterator erase(const_iterator position);  
//iterator erase(const_iterator first, const_iterator last);  
//void swap(vector& x);  
//template <class... Args>  
//iterator emplace(const_iterator position, Args&&... args);  
//template <class... Args>  
//void emplace_back(Args&&... args);  
//template <class... Args>  
//void emplace_back(Args&&... args);  
//void clear() noexcept;  
#include<iostream>  
#include<vector>  
using namespace std;  
int main()  
{  
    vector<int> first_vector;  
    vector<int> second_vector;  
    for (int i = 1; i <= 10; i++)  
        first_vector.push_back(i);  
    //刪除第四個元素  
    first_vector.erase(first_vector.begin() + 3);  

    //刪除第5到第七個元素  
    first_vector.erase(first_vector.begin() + 4, first_vector.begin() + 6);  

    for each (auto var in first_vector)  
    {  
        cout << var << " ";  
    }  
    cout << endl;  

    first_vector.swap(second_vector);  
    cout << second_vector.size();  
    cout << endl;  

    //在起始位置插入一個100  
    second_vector.emplace(second_vector.begin(), 100);  
    for each (auto var in second_vector)  
    {  
        cout << var << " ";  
    }  
    cout << endl;  

    //在末尾插入一個200  
    second_vector.emplace_back(200);  
    for each (auto var in second_vector)  
    {  
        cout << var << " ";  
    }  
    cout << endl;  

    second_vector.clear();  
    cout << second_vector.size();  
    cout << endl;  
    return 0;  
}  

輸出：
1 2 3 5 8 9 10
7
100 1 2 3 5 8 9 10
100 1 2 3 5 8 9 10 200
0

Allocator

//函數簽名  
//allocator_type get_allocator() const noexcept;  
#include<iostream>  
#include<vector>  
using namespace std;  
int main()  
{  
    vector<int> my_vector;  
    int *p;  
    unsigned int i;  
    //用vector的allocator分配五個int的空間  
    p = my_vector.get_allocator().allocate(5);  

    for (i = 0; i != 5; i++)  
        my_vector.get_allocator().construct(&p[i], i);  

    for (int i = 0; i != 5; i++)  
        cout << p[i] << " ";  
    cout << endl;  

    for (i = 0; i != 5; i++)  
        my_vector.get_allocator().destroy(&p[i]);  
    my_vector.get_allocator().deallocate(p,5);  

    return 0;  
}  

輸出：
0 1 2 3 4

非成員函數

//函數簽名  
//(1)  
//template <class T, class Alloc>  
//bool operator== (const vector<T, Alloc>& lhs, const vector<T, Alloc>& rhs);  
//(2)  
//template <class T, class Alloc>  
//bool operator!= (const vector<T, Alloc>& lhs, const vector<T, Alloc>& rhs);  
//(3)  
//template <class T, class Alloc>  
//bool operator<  (const vector<T, Alloc>& lhs, const vector<T, Alloc>& rhs);  
//(4)  
//template <class T, class Alloc>  
//bool operator<= (const vector<T, Alloc>& lhs, const vector<T, Alloc>& rhs);  
//(5)  
//template <class T, class Alloc>  
//bool operator>  (const vector<T, Alloc>& lhs, const vector<T, Alloc>& rhs);  
//(6)  
//template <class T, class Alloc>  
//bool operator>= (const vector<T, Alloc>& lhs, const vector<T, Alloc>& rhs);  
#include<iostream>  
#include<vector>  
using namespace std;  
int main()  
{  
    vector<int> first_vector = { 1,2,3 };  
    vector<int> second_vector = { 3,2,1 };  

    if (first_vector == second_vector)   
        cout << "first_vector and second_vector are equal\n";  
    if (first_vector != second_vector)   
        cout << "first_vector and second_vector are not equal\n";  
    if (first_vector< second_vector)   
        cout << "first_vector is less than second_vector\n";  
    if (first_vector> second_vector)   
        cout << "first_vector is greater than second_vector\n";  
    if (first_vector <= second_vector)   
        cout << "first_vector is less than or equal to second_vector\n";  
    if (first_vector >= second_vector)   
        cout << "first_vector is greater than or equal to second_vector\n";  
    return 0;  
}  

輸出：
first_vector and second_vector are not equal
first_vector is less than second_vector
first_vector is less than or equal to second_vector

//函數簽名  
//template <class T, class Alloc>  
//void swap(vector<T, Alloc>& x, vector<T, Alloc>& y);  
#include<iostream>  
#include<vector>  
using namespace std;  
int main()  
{  
    //非成員函數的swap()效率小於等於成員函數的swap(),所以建議用成員函數版的  
    vector<int> first_vector = { 1,2,3 };  
    vector<int> second_vector = { 3,2,1 };  

    swap(first_vector, second_vector);  
    for each (auto var in first_vector)  
    {  
        cout << var << " ";  
    }  
    cout << endl;  
    for each (auto var in second_vector)  
    {  
        cout << var << " ";  
    }  
    cout << endl;  
    return 0;  
}  

輸出：
3 2 1
1 2 3