A summary of vector usage in C + +

  This article mainly introduces the vector is a very useful container in C + +, the following is a summary of the container  

1 Basic Operation   (1) header file #include<vector>.   (2) Create vector object,vector<int> VEC;   (3) Tail Insert number: Vec.push_back (a);   (4) using subscript to access elements,cout<<vec[0]<<endl; remember that subscripts start at 0.   (5) Accessing elements using iterators.     Code is as follows: Vector<int>::iterator it; For (It=vec.begin (); It!=vec.end (); it++)     cout<<*it<<endl;     (6) Insert element:    vec.insert (Vec.begin () +i,a); Insert a in front of the i+1 element;   (7) Delete element:    vec.erase (Vec.begin () +2); Delete 3rd element   Vec.erase (Vec.begin () +i,vec.end () +j); Delete interval [I, J-1]; Range starting from 0   (8) vector size: vec.size ();   (9) Empty: Vec.clear ();   2   Vector elements can not only make int,double,string, but also structure, but note: The structure is defined as global, otherwise there will be an error. The following is a short program code:       Code as follows: #include <stdio.h> #include <algorithm> #include <vector> # Include<iostream> using namespace std;   typedef struct RECT {    int id;     int length;     int width;  //for vector element is structure Body, you can define the comparison function within the structure, sorted by Id,length,width ascending order below. 　　BOOL operator< (const rect &a)  const     {        (id!=a.id)   &NBSP ;         return id<a.id;         else         {            if (Length!=a.leng TH)                 return length<a.length;             else                 return WIDTH<A.W Idth;        }    }rect;   int main () {    vector<rect> VEC     Rect Rect;     rect.id=1;     rect.length=2;     rect.width=3;     Vec.push_back (rect);     Vector<rect>::iterator it=vec.begin ();     cout<< (*it) .id<< ' << (*it) .length<< ' << (*it) .width<<endl;       return 0;  }     3   algorithm   (1) Flip elements using reverse: Header file #include<algorithm>   reverse (Vec.begin (), Vec.end ()); Flip the element (in vector, If two iterators are required in a function, the   generally does not include the latter.)   (2) Using sort sorting: Requires header file #include<algorithm&gt,   sort (vec.begin (), Vec.end ());(default is in ascending order, that is, from small to large.   can be compared by overriding the sort comparison function in descending order:   Defining the Sort comparison function:     Copy code code as follows: BOOL Comp (const int &a,const int &b) {&NB Sp   Return a>b;   When called: Sort (Vec.begin (), Vec.end (), Comp), sorted in descending order.