【C++】-- STL之vector详解（二）

1. void test_vector3()
2. {
3. size_t sz;
4.     std::vector<int> foo;
5.     sz = foo.capacity();
6. 
7.     std::cout << "making foo grow:\n";
8. 
9. for (int i = 0; i < 100; i++)
10.     {
11.         foo.push_back(i);
12. if (sz != foo.capacity())
13.         {
14.             sz = foo.capacity();
15.             std::cout << "capacity changed:" << sz << endl;
16.         }
17.     }
18. }

1. void reserve (size_type n);//开辟n个元素空间
2. void resize (size_type n, value_type val = value_type());//开辟n个元素空间，并将每个元素默认初始化为val

1. void test_vector3()
2. {
3. size_t sz;
4.     std::vector<int> foo;
5.     sz = foo.capacity();
6.     foo.reserve(100);
7. 
8.     std::cout << "making foo grow:\n";
9. 
10. for (int i = 0; i < 100; i++)
11.     {
12.         foo.push_back(i);
13. if (sz != foo.capacity())
14.         {
15.             sz = foo.capacity();
16.             std::cout << "capacity changed:" << sz << endl;
17.         }
18.     }
19. }

1.     vector<int> v1;
2.     v1.reserve(10);
3. 
4.     vector<int> v2;
5.     v2.resize(10);

size_type size() const;

1.     vector<int> v5;
2. //插入4个元素
3.     v5.push_back(1.1);
4.     v5.push_back(2.2);
5.     v5.push_back(3.3);
6.     v5.push_back(4.4);
7.     cout << v5.size() << endl;

bool empty() const;

cout << v5.empty() << endl;

1. void push_back (const value_type& val);//尾插元素
2. void pop_back();//尾删元素

1.     v5.push_back(5.5);
2. PrintVector(v5);
3. 
4.     v5.pop_back();
5. PrintVector(v5);

1. iterator insert (iterator position, const value_type& val);//插入val到position位置
2. void insert (iterator position, size_type n, const value_type& val);//将n个val插入到position位置
3. template <class InputIterator>
4. void insert (iterator position, InputIterator first, InputIterator last);//将值为InputIterator的first到last之间的元素插入到position位置

1.     vector<double> v5;
2. //插入4个float元素
3.     v5.push_back(1.1);
4.     v5.push_back(2.2);
5.     v5.push_back(3.3);
6.     v5.push_back(4.4);
7.     v5.push_back(5.5);
8. 
9.     v5.insert(v5.end(), 6.6);//在v5末尾插入6.6
10. PrintVector(v5);
11. 
12.     v5.insert(v5.begin(), 2,0);//在v5开头插入2个0
13. PrintVector(v5);
14. 
15.     vector<double> v6;
16.     v6.push_back(7.7);
17.     v6.push_back(8.8);
18. 
19.     v5.insert(v5.begin(), v6.begin(),v6.end());//在v5开头插入v6
20. PrintVector(v5);

1. iterator erase (iterator position);//删除某一位置元素
2. iterator erase (iterator first, iterator last);//删除迭代器first和last之间的元素

1.     v5.erase(v5.begin());//删除v5开头元素
2. PrintVector(v5);
3. 
4.     v5.erase(v5.begin(), v5.begin()+2);//从v5开头删除2个元素
5. PrintVector(v5);

1. template <class InputIterator, class T>
2. InputIterator find (InputIterator first, InputIterator last, const T& val);//在InputIterator迭代器first和last区间内查找val元素的位置

1.     vector<double>::iterator pos = find(v5.begin(), v5.begin() + 3, 1.1);//在第一个元素和第四个元素（左闭右开，不包含第四个元素）之间查找值为1.1的元素位置
2.     v5.erase(pos);//删除1.1位置的元素，即删除1.1
3. 
4. PrintVector(v5);

void swap (vector& x);

1.     vector<int> v1;
2.     v1.push_back(20);
3. 
4.     v.swap(v1);//交换v和v1的元素
5. 
6. PrintVector(v);
7. PrintVector(v1);

1. template <class T> void swap (T& a, T& b);
2. {
3.     T c(a); a=b; b=c;
4. }