1 //vector  -- simple vector, @CopyLeft by tsaiwn@csie.nctu.edu.tw
  2 //Demo how vector works; 但這簡易版不會丟出 Exception
  3 #ifndef __MY_VECTOR__
  4 #define __MY_VECTOR__
  5 //to ensure this file will be only "included" once
  6 #include<iostream>
  7 #include<algorithm>    // sort( )
  8 #include<stdexcept>   // standard exception classes
  9 using namespace std;
 10 
 11 template<class T>
 12 class vector {
 13    T* pdata;    // pointer can be used like an array
 14    int _size, _capc;    // store my size and my capacity
 15    void getMoreSpace( ) { //get new memory, copy old to new, drop old
 16       _capc += _capc;  // double space
 17       T* p = new T[_capc];
 18       T *old = pdata;  // for later use
 19       pdata = p;   // point to new data Area
 20       memcpy((void*)pdata, (void*)old, (sizeof(T) * _size)); // byte
 21       delete [ ] old;  // release Old data memory area
 22       return; // done
 23    }//getMoreSpace(
 24 public: 
 25    typedef T* iterator;
 26    vector(int n=10) {_size=0; _capc=n; pdata = new T[_capc]; }
 27         // default initial capacity in C++ STL is 0; in Java is 10
 28    vector(T*a, T*b) {
 29       _size=_capc= b-a;
 30       pdata = new T[_capc];
 31       memcpy((void*)pdata, (void*)a, (sizeof(T) * _size)); // byte
 32    } // constructor
 33    int size( ) { return _size; }
 34    int capacity( ) { return _capc; }
 35    T* begin( ) { return pdata; }
 36    T* end( ) { return pdata+ _size; }
 37    T& front( ) { return *pdata; }
 38    T& back( ) { return pdata[_size-1]; }   // *(pdata+ _size -1)
 39    void push_back(const T a) {
 40        if( _size == _capc ) getMoreSpace( );  // ensure enough space
 41        pdata[_size] = a;    // append data into tail
 42        _size++;  // advance one data unit
 43    }//push_back
 44    void pop_back( ) {
 45        if( _size <= 0 ) return;   // Nothing in the vector
 46        _size--;
 47    }//pop_back
 48    void add(const T a) { push_back(a); }   // nick name
 49    T& operator[ ](int n) { cout <<" X "; return  pdata[n]; } /////
 50    T& at(int n) { cout <<" A "; 
 51       if(n < 0) throw range_error("vector");
 52       if(n >= _size) throw range_error("vector");
 53       return  pdata[n]; 
 54    } // at(
 55   // Note that the operator[ ] and at function should return reference, 
 56    // .. so that it can be used as a "Left value"
 57 };  // class vector
 58 #endif