# The simple realization of C + + vector

Source: Internet
Author: User
Tags int size

It is simple because it does not implement the allocate class and uses a simple malloc to allocate memory.

Iterator also employs a direct value_type pointer, but retains the basic interface and method of vectors. It is helpful to understand the vector working principle.

The code and test code are as follows:

#include "stdafx.h" template < class T > class vector{enum{space_capacity = 4};//Initial capacity public:///////////////// Constructors and Destructors/////////////////////////////////////// Avoid implicit type conversions with explicit explicit vector (int size = 0): m_size (size), M_capaci
Ty (size + space_capacity) {_p = new t[m_capacity];
//copy constructor Vector (const vector & RHS): _p (NULL) {operator= (RHS);}

~vector () {delete [] _p} Operator////////////////////////// Const VECTOR & operator= (const vector & RHS) {if (thi
S!= &rhs) {//If it is itself, then no longer operate the delete [] _p;
M_size = Rhs.size ();

M_capacity = Rhs.capacity ();
_p = new t[capacity ()];
for (int k = 0; k < m_size; k++)//copy element _p[k] = Rhs._p[k];
return *this;	} T & operator[] (int index) {return _p[index];}
Const T & operator[] (int index) const {return _p[index];} Pointers, iterator operations/////////////// typedef T * iterator;//replaces iterators with native pointers typedef const T * C
Onst_iterator;
Iterator begin () {return &_p[0];}
Const_iterator begin () const {return &_p[0];}
Iterator End () {return &_p[m_size];}

Const_iterator End () const {return &_p[m_size];} Insert element, popup element/////////////////// void push_back (const T & x) {if (m_size = = M_capaci
ty) Reallocate (2*m_capacity + 1);
_p[m_size++] = x;
} void Pop_back () {m_size--;} //////////////////////////////////////////////////////////////////////////////Property interface////////////////////////////////////////////////////////////////////////////////int size () const {return m _size;
int capacity () const {return m_capacity}
BOOL Empty () const {return size () = 0;} Const T & Back () const {return _p[m_size-1];} private:int m_size; The number of elements int m_capacity; Capacity T *_p; Resource//////////////////////////////////////////////////////////////////////////////////memory allocation (allocator simplification processing) pointing to new assignment/// Each time there is not enough space, you regain twice times the current capacity of space void
Resize (int newsize) {if (NewSize > M_capacity) reallocate (newsize*2);
M_size = newsize;

//Get new space, copy, release old data void reallocate (int newcapacity) {if (Newcapacity < m_size) return;
T *oldarray = _p;
_p = new t[newcapacity];
for (int k = 0; k < m_size; k++) _p[k] = oldarray[k];
m_capacity = newcapacity;
delete [] oldarray;

}
};
int main (int argc, char *argv[]) {vector<int> V;V.push_back (4);
V.push_back (5);
Vector<int>::iterator it;
For (It=v.begin (); It!=v.end (); it++) {printf ("The data is%d\n", *it);
} _getch ();
return 0;
}

Related Keywords:
Related Article

The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion; products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the content of the page makes you feel confusing, please write us an email, we will handle the problem within 5 days after receiving your email.

If you find any instances of plagiarism from the community, please send an email to: info-contact@alibabacloud.com and provide relevant evidence. A staff member will contact you within 5 working days.

## A Free Trial That Lets You Build Big!

Start building with 50+ products and up to 12 months usage for Elastic Compute Service

• #### Sales Support

1 on 1 presale consultation

• #### After-Sales Support

24/7 Technical Support 6 Free Tickets per Quarter Faster Response

• Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.