数组类的创建——DynamicArray.h

完成DynamicArray类的具体实现

DynamicArray设计要点
——类模板
　　动态确定内部数组空间的大小
　　实现函数返回数组长度
　　拷贝构造和赋值操作

DynamicArray类的声明

template <typename T>

class DynamicArray : public Array<T>

{

protected:

    T m_length;

public:

    DynamicArray(int length);

    //拷贝构造和赋值操作

    DynamicArray(const DynamicArray<T>& obj );

    DynamicArray<T>& operator= (const DynamicArray<T>& obj);

    int length() const;

    void resize(int length);  //动态重置数组的长度

    ~DynamicArray();

};

#ifndef DYNAMICARRAY_H

#define DYNAMICARRAY_H

#include "Array.h"

#include "Exception.h"

namespace DTLib

{

template <typename T>

class DynamicArray : public Array<T>

{

protected:

    T m_length;

public:

    DynamicArray(int length)

    {

        this->m_array = new T[length];

        if(this->m_array != NULL)

        {

            this->m_length = length;

        }

        else

        {

            THROW_EXCEPTION(IndexOutOfBoundsException, "No memory to create DynamicArray object...");

        }

    }

    //拷贝构造和赋值操作

    DynamicArray(const DynamicArray<T>& obj )

    {

        this->m_array = new T[obj.m_length];

        if(this->m_array != NULL)

        {

            this->m_length = obj.m_length;

            for(int i=; i<m_length; i++)

            {

                this->m_array[i] = obj.m_array[i];

            }

        }

        else

        {

            THROW_EXCEPTION(IndexOutOfBoundsException, "No memory to create DynamicArray object...");

        }

    }

    DynamicArray<T>& operator= (const DynamicArray<T>& obj)

    {

        if(this != &obj)

        {

            T* array = new T[obj.m_length];

            if(array != NULL)

            {

                for(int i=; i<obj.m_length; i++)

                {

                    array[i] = obj.m_array[i];

                }

                T* temp = this->m_array;

                this->m_array = array;

                this->m_length = obj.m_length;

                delete[] temp;

            }

            else

            {

                THROW_EXCEPTION(IndexOutOfBoundsException, "No memory to copy DynamicArray object...");

            }

        }

        return *this;

    }

    int length() const

    {

        return m_length;

    }

    void resize(int length) //动态重置数组的长度

    {

        if(m_length != length)

        {

            T* array = new T[length];

            if(array != NULL)

            {

                int size = (length < m_length) ? length : m_length;

                for(int i=; i<size; i++)

                {

                    array[i] = this->m_array[i];

                }

                T* temp = this->m_array;

                this->m_array = array;

                this->m_length = length;

                delete[] temp;

            }

            else

            {

                THROW_EXCEPTION(IndexOutOfBoundsException, "No memory to resize DynamicArray object...");

            }

        }

    }

    ~DynamicArray()

    {

        delete[] this->m_array;

    }

};

}

#endif // DYNAMICARRAY_H

测试：

#include <iostream>

#include "DynamicArray.h"

using namespace std;

using namespace DTLib;

int main()

{

    DynamicArray<int> sl();

    for(int i=; i<sl.length(); i++)

    {

        sl[i] = i * i;

    }

    for(int i=; i<sl.length(); i++)

    {

        cout << sl[i] << endl;

    }

    cout << endl;

    DynamicArray <int> s2();

    s2 = sl;

    for(int i=; i<s2.length(); i++)

    {

        cout << s2[i] << endl;

    }

    cout << endl;

    s2.resize();

    for(int i=; i<; i++)

    {

        cout << s2[i] << endl;

    }

    return ;

}

代码优化：

DynamicArray类中的函数实现存在重复的逻辑，如何进行代码优化？

重复代码逻辑的抽象
——init
　　对象构造时的初始化操作
——copy
　　在堆空间中申请新的内存，并执行拷贝操作
——update
　　将指定的堆空间作为内部存储数组使用

#ifndef DYNAMICARRAY_H

#define DYNAMICARRAY_H

#include "Array.h"

#include "Exception.h"

namespace DTLib

{

template <typename T>

class DynamicArray : public Array<T>

{

protected:

    T m_length;

    T* copy(T* array, int len, int newlen)

    {

        T* ret = new T[newlen];

        if(ret != NULL)

        {

            int size = (len < newlen) ? len : newlen;

            for(int i=; i<size; i++)

            {

                ret[i] = array[i];

            }

        }

        return ret;

    }

    void update(T* array, int length)

    {

        if(array != NULL)

        {

            T* temp = this->m_array;

            this->m_array = array;

            this->m_length = length;

            delete[] temp;

        }

        else

        {

            THROW_EXCEPTION(IndexOutOfBoundsException, "No memory to resize DynamicArray object...");

        }

    }

    void init(T* array, int length)

    {

        if(array != NULL)

        {

            this->m_array = array;

            this->m_length = length;

        }

        else

        {

            THROW_EXCEPTION(IndexOutOfBoundsException, "No memory to create DynamicArray object...");

        }

    }

public:

    DynamicArray(int length)

    {

        init(new T(length),length);

    }

    //拷贝构造和赋值操作

    DynamicArray(const DynamicArray<T>& obj )

    {

        init( copy(obj.m_array,obj.m_length,obj.m_length),obj.m_length);

    }

    DynamicArray<T>& operator= (const DynamicArray<T>& obj)

    {

        if(this != &obj)

        {

            update( copy(obj.m_array,obj.m_length,obj.m_length),obj.m_length);

        }

        return *this;

    }

    int length() const

    {

        return m_length;

    }

    void resize(int length) //动态重置数组的长度

    {

        if(m_length != length)

        {

            update(copy(this->m_array, m_length ,length),length);

        }

    }

    ~DynamicArray()

    {

        delete[] this->m_array;

    }

};

}

#endif // DYNAMICARRAY_H

巴特西

数组类的创建——DynamicArray.h

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