C + + vector <vector> Learning

In my opinion, this thing about vectors should be an enhanced version of the array.

Need header file when using #include <vector>

Advantages of the vector container: ① is not prone to overflow, it automatically adjusts the data size to accommodate the element you put in ② is that it has many ways to manipulate the elements

Declaration & Initialization:

Vector < type > name

Cases:

Vector <int > A; //Declare an int type vector a

Vector <int > B (10); //declaration of type int vector b with size 10

Vector <int > B (a); //using vector A to initialize vector b

Vector <int > C (10,2); //Declaration size is 10, and the data is initialized to 2 of the vector C

　　vector <int > D (C.begin (), C.begin () +2); //using vector C No. 0, 1 element initialization vector D A total of 2 elements

　　Of course, you can use an array to initialize the initial, here is not given an example;

Input, Output:

　　Like arrays, you can use Cin,cout to perform input and output operations on vectors and, of course, to take advantage of functions

cin>>a[0];

Basic Functions & Operations:

. Size //Returns the number of elements in a vector

. Empty //return vector is null

. Clear //empty elements in a vector

. Erase //delete a (some) element

= //copy vector

= = //Determine if vectors are equal

. Insert //Inserts an element at a location

　　. push_back //Inserts an element at the last position of the current vector (can insert a vector for a multidimensional vector)

. Swap //exchange vector

　. Begin (). End () //Returns the starting and the bottom of a vector element

　　all of the above operations are vectors (nonsense) (￣ε (#￣) ☆╰╮ (￣▽￣///)

Two (multi)-dimensional vectors:

In fact, the vector type is used in the declaration type, and there is no other difference between the operation and the one vector, which can be used as a two (multi)-dimensional array

Example: Vector <vector <int > >a

　　　　　　　　　　　　Ps:↑ here must have a space, no words seem to be because the priority will be error;

　　(╯‵-′) ╯︵┻━┻ This white background color how to go AH

Other:

About Size_type:

　　

　　A type defined by the string class type and the vector class type that holds the length of any string object or vector object, and the standard library type defines size_type as the unsigned type.

------from Wikipedia

Under the thought, is actually because the data storage does not necessarily according to 1 size to allocate, specially has made a to adapt, to save the vector length

Example:vector< vector<int> >::size_type u

For (vector< vector<int> >::size_type u = 0; u < a.size (); u++); //I,j used as a normal count

　　

　About iterators:

　　Used to traverse the data in a vector

Example: Vector <int >::iterator b

For (B=a.begin (); B!=a.end (); b++);

2016.04.03

C + + vector <vector> Learning