array.cpp

C++ PRIME书中的原代码,看本书时可以学习的例子.

#include <cassert>

#include "Array.h"
 
template <class elemType>
const int Array<elemType>::DefaultArraySize = 12;
 
template <class elemType>
    void Array<elemType>::init( const elemType *array, int sz )
{
    if ( ! array ) { _size = 0; _ia = 0; }
    if ( sz < 1 ) sz = 1;
 
    _size = sz;
    _ia = new elemType[ _size ];
 
    for ( int ix = 0; ix < _size; ++ix )
          _ia[ ix ] = array[ ix ];
}
 
template <class elemType> Array<elemType>&
    Array<elemType>::operator=( const Array<elemType> &iA )
{
    if ( this == &iA )
         return *this;
 
    delete[] _ia;
    init( iA._ia, iA._size );
    return *this;
}
 
template <class elemType> ostream&
    operator<<( ostream &os, Array<elemType> &ar )
{
    return ar.print( os );
}
 
template <class elemType>
    ostream& Array<elemType>::print( ostream &os ) const
{
    const int lineLength = 12;
    os << "( " << _size << " )< ";
 
    for ( int ix = 0; ix < _size; ++ix )
    {
          if ( ix % lineLength == 0 && ix )
               os << "\n\t";
 
          os << _ia[ ix ];
          // don't generate comma for last item on line
          // nor for the last element of the array
          if ( ix % lineLength != lineLength-1 && ix != _size-1 )
               os << ", ";
    }
 
    os << " >\n";
    return os;
}
 
template <class elemType>
    void Array<elemType>::grow()
{
    elemType *oldia = _ia;
    int oldSize = _size;
 
    _size = oldSize + oldSize/2 + 1;
    _ia   = new elemType[_size];
 
    int ix;
    for ( ix = 0; ix < oldSize; ++ix)
          _ia[ix] = oldia[ix];
 
    for ( ; ix < _size; ++ix )
          _ia[ix] = elemType();
 
    delete[] oldia;
}
 
template <class elemType>
    elemType Array<elemType>::min( )
{
    assert( _ia != 0 );
    elemType min_val = _ia[0];
 
    for ( int ix = 1; ix < _size; ++ix )
          if ( _ia[ix] < min_val )
               min_val = _ia[ix];
 
    return min_val;
}
 
template <class elemType>
    elemType Array<elemType>::max()
{
    assert( _ia != 0 );
    elemType max_val = _ia[0];
 
    for ( int ix = 1; ix < _size; ++ix )
          if ( max_val < _ia[ix] )
               max_val = _ia[ix];
 
    return max_val;
}
 
template <class elemType>
    int Array<elemType>::find( elemType val )
{
    for ( int ix = 0; ix < _size; ++ix )
          if ( val == _ia[ix] )
               return ix;
 
    return -1;
}
 
template <class elemType>
    void Array<elemType>::swap( int i, int j )
{
     elemType tmp = _ia[i];
     _ia[i] = _ia[j];
     _ia[j] = tmp;
}
 
template <class elemType>
    void Array<elemType>::sort( int low, int high )
{
    if ( low >= high ) return;
    int lo = low;
    int hi = high + 1;
    elemType elem = _ia[low];
 
    for ( ;; ) {
         while ( _ia[++lo] < elem ) ;
         while ( _ia[--hi] > elem ) ;
         if ( lo < hi )
              swap( lo,hi );
         else break;
    }
 
    swap( low, hi );
    sort( low, hi-1 );
    sort( hi+1, high );
}