C + + vector usage (RPM)

in the C + + in which Vector is a very useful container, here is a summary of the container.

1 Basic Operations

(1) header File #include <vector>.

(2) Create Vector objects, vector<int> Vec;

(3) trailing insert Number: Vec.push_back (a);

(4) use subscript to access elements, cout<<vec[0]<<endl; Remember that the subscript is from 0 the beginning.

(5) using 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); in section i+1 elements in front of the insert A;

(7) To Delete an element: ??? Vec.erase (Vec.begin () +2); Delete section 3 an element

vec.erase (Vec.begin () +i,vec.end () +j); Delete Interval [i,j-1]; interval from 0 Start

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

(9) Clear : Vec.clear ();

2

Vector element can not only make int,double,string, It can also be a struct, but be aware that the struct is defined as global, otherwise an error occurs. Here is a short program code:

#include <stdio.h>

#include <algorithm>

#include <vector>

#include <iostream>

Usingnamespace std;

?

typedef struct rect

{

int ID;

int length;

Span style= "color:blue; Font-family:courier new ">int width;

// for a vector element is a struct, you can define a comparison function within a struct, followed by id,length,width ascending sort.
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;

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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;

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return0;

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}

? 3? algorithm

(1) flip element with reverse : Requires header file #include <algorithm>

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

usually the last one does not contain .)

(2) Use Sort sort: Requires header file #include <algorithm> ,

sort (Vec.begin (), Vec.end ());( By default it is sorted 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;
}
when called : Sort (Vec.begin (), Vec.end (), Comp) , so it's sorted in descending order.

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Original: http://www.cnblogs.com/wang7/archive/2012/04/27/2474138.html

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C + + vector usage (RPM)