array.h

游戏开发数据结构Data Structures for Game Programmers

// ============================================================================
// Data Structures For Game Programmers
// Ron Penton
// Array.h
// This is the basic 1D array class.
// ============================================================================
#ifndef ARRAY_H
#define ARRAY_H

#include <stdio.h>

template<class Datatype>
class Array
{
public:

// -------------------------------------------------------
// Name:        Array::Array
// Description: This constructs the array.
// Arguments:   - p_size: the size of the array.
// -------------------------------------------------------
    Array( int p_size )
    {
        // allocate enough memory for the array.
        m_array = new Datatype[p_size];

        // set the size variable
        m_size = p_size;
    }


// -------------------------------------------------------
// Name:        Array::~Array
// Description: This destructs the array.
// -------------------------------------------------------
    ~Array()
    {
        // if the array is not null, delete it.
        if( m_array != 0 )
            delete[] m_array;

        // clear the pointer, just in case we ever modify this.
        m_array = 0;
    }


// -------------------------------------------------------
// Name:        Array::Resize
// Description: This resizes the array to a new size.
// Arguments:   - p_size: the new size of the array.
// -------------------------------------------------------
    void Resize( int p_size )
    {
        // create a new array with the new size
        Datatype* newarray = new Datatype[p_size];

        // if the new array wasn't allocated, then just return
        // and don't change anything.
        if( newarray == 0 )
            return;

        // determine which size is smaller.
        int min;
        if( p_size < m_size )
            min = p_size;
        else
            min = m_size;

        // loop through and copy everything possible over.
        int index;
        for( index = 0; index < min; index++ )
            newarray[index] = m_array[index];

        // set the size of the new array
        m_size = p_size;

        // delete the old array.
        if( m_array != 0 )
            delete[] m_array;

        // copy the pointer over.
        m_array = newarray;
    }


// -------------------------------------------------------
//  Name:         Array::operator[]
//  Description:  gets a reference to the item at given 
//                index.
//  Arguments:    - p_index: index of the item to get.
//  Return Value: reference to the item at the index.
// -------------------------------------------------------
    Datatype& operator[] ( int p_index )
    {
        return m_array[p_index];
    }



// -------------------------------------------------------
//  Name:         Array::Insert
//  Description:  Inserts a cell inbetween two others.
//  Arguments:    - p_item: item to insert
//                - p_index: index to insert at.
// -------------------------------------------------------
    void Insert( Datatype p_item, int p_index )
    {
        int index;
        
        // move everything after p_index up by one cell.
        for( index = m_size - 1; index > p_index; index-- )
            m_array[index] = m_array[index - 1];

        // insert the item.
        m_array[p_index] = p_item;
    }



// -------------------------------------------------------
//  Name:         Array::Remove
//  Description:  Removes a cell
//  Arguments:    - p_index: index to remove.
// -------------------------------------------------------
    void Remove( int p_index )
    {
        int index;

        // move everything after p_index down by one cell.
        for( index = p_index + 1; index < m_size; index++ )
            m_array[index - 1] = m_array[index];
    }



// -------------------------------------------------------
//  Name:         Array::Size
//  Description:  gets the size of the array.
//  Arguments:    None.
//  Return Value: the size of the array.
// -------------------------------------------------------
    int Size()
    {
        return m_size;
    }


// -------------------------------------------------------
//  Name:         Array::WriteFile
//  Description:  Writes an array to disk
//  Arguments:    The Filename
//  Return Value: true on success, false on failure
// -------------------------------------------------------
    bool WriteFile( const char* p_filename )
    {
        FILE* outfile = 0;
        int written = 0;

        // open the file
        outfile = fopen( p_filename, "wb" );

        // return if it couldn't be opened
        if( outfile == 0 )
            return false;

        // write the array and close thef ile
        written = fwrite( m_array, sizeof( Datatype ), m_size, outfile );
        fclose( outfile );

        // if we didn't write the number of items we expected,
        // return failure
        if( written != m_size )
            return false;

        // return success.
        return true;
    }
    

// -------------------------------------------------------
//  Name:         Array::ReadFile
//  Description:  reads an array from disk
//  Arguments:    The Filename
//  Return Value: true on success, false on failure
// -------------------------------------------------------
    bool ReadFile( const char* p_filename )
    {
        FILE* infile = 0;
        int read = 0;

        // open the file
        infile = fopen( p_filename, "rb" );

        // return if it couldn't be opened
        if( infile == 0 )
            return false;

        // read the array and close the file
        read = fread( m_array, sizeof( Datatype ), m_size, infile );
        fclose( infile );

        // if we didn't read the number of items we expected,
        // return failure
        if( read != m_size )
            return false;

        // return success
        return true;
    }



// -------------------------------------------------------
// Name:        Array::m_array
// Description: This is a pointer to the array.
// -------------------------------------------------------
    Datatype* m_array;


// -------------------------------------------------------
// Name:        Array::m_size
// Description: the current size of the array.
// -------------------------------------------------------
    int m_size;
};




#endif