//vector  -- simple vector, @CopyLeft by tsaiwn@csie.nctu.edu.tw
//Demo how vector works; 但這簡易版不會丟出 Exception
#ifndef __MY_VECTOR__
#define __MY_VECTOR__
//to ensure this file will be only "included" once
#include<iostream>
#include<algorithm>    // sort( )
#include<stdexcept>   // standard exception classes
using namespace std;

template<class T>
class vector {
   T* pdata;    // pointer can be used like an array
   int _size, _capc;    // store my size and my capacity
   void getMoreSpace( ) { //get new memory, copy old to new, drop old
      _capc += _capc;  // double space
      T* p = new T[_capc];
      T *old = pdata;  // for later use
      pdata = p;   // point to new data Area
      memcpy((void*)pdata, (void*)old, (sizeof(T) * _size)); // byte
      delete [ ] old;  // release Old data memory area
      return; // done
   }//getMoreSpace(
public: 
   typedef T* iterator;
   vector(int n=10) {_size=0; _capc=n; pdata = new T[_capc]; }
        // default initial capacity in C++ STL is 0; in Java is 10
   vector(T*a, T*b) {
      _size=_capc= b-a;
      pdata = new T[_capc];
      memcpy((void*)pdata, (void*)a, (sizeof(T) * _size)); // byte
   } // constructor
   int size( ) { return _size; }
   int capacity( ) { return _capc; }
   T* begin( ) { return pdata; }
   T* end( ) { return pdata+ _size; }
   T& front( ) { return *pdata; }
   T& back( ) { return pdata[_size-1]; }   // *(pdata+ _size -1)
   void push_back(const T a) {
       if( _size == _capc ) getMoreSpace( );  // ensure enough space
       pdata[_size] = a;    // append data into tail
       _size++;  // advance one data unit
   }//push_back
   void pop_back( ) {
       if( _size <= 0 ) return;   // Nothing in the vector
       _size--;
   }//pop_back
   void add(const T a) { push_back(a); }   // nick name
   T& operator[ ](int n) { cout <<" X "; return  pdata[n]; } /////
   T& at(int n) { cout <<" A "; 
      if(n < 0) throw range_error("vector");
      if(n >= _size) throw range_error("vector");
      return  pdata[n]; 
   } // at(
  // Note that the operator[ ] and at function should return reference, 
   // .. so that it can be used as a "Left value"
};  // class vector
#endif