Substitution of arrays--template vector, use of array

In C + +, vector is a very useful container, and here is a summary of the container.

1 Basic operations

(1) header file #include<vector>.

(2) Create vector object,vector<int> VEC;

(3) Insert number at tail: vec.push_back (a);

(4) Use subscript to access the element,cout<<vec[0]<<endl; remember that the subscript is starting from 0.

(5) Use iterators to access elements.

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 first 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]; interval starting from 0

(8) Vector size: vec.size ();

(9) Empty: Vec.clear ();

2

The elements of the

vector can not only make int,double,string, but also structs, but be aware that the struct is defined as global, or else an error occurs. Here is a short code for the program:

#include <stdio.h> #include <algorithm> #include <vector> #include <iostream>using  namespace std;typedef struct rect{        int id;         int length;       　　 int width;　　For vector elements that are structural, you can define a comparison function within the structure, sorted in ascending order of Id,length,width. bool operator<  (Const rect &a)   const    {         if (id!=a.id)              return id<a.id;        else         {             if (length!=a.length)                  return length<a.length;            else                 return width<a.width;         }    }}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 the element with reverse: Requires a header file #include<algorithm>

Reverse (Vec.begin (), Vec.end ()); Flips the element (in a vector, if two iterators are required in a function,

Usually the latter is not included.)

(2) Sorting by using sort: Requires header file #include<algorithm>

Sort (Vec.begin (), Vec.end ());(by default in ascending order, that is, from small to large).

You can compare functions in descending order by overriding the sort comparison, as follows:

To define a sort comparison function:

BOOL Comp (const int &A,CONST int &b)
{
Return a>b;
}
Called When: Sort (Vec.begin (), Vec.end (), Comp), so that it is sorted in descending order.

Substitution of arrays--template vector, use of array