【析构函数写法】如何使用析构函数释放类成员函数申请的堆内存

Question

标题：【析构函数写法】如何使用析构函数释放类成员函数申请的堆内存

环境：win7 64位/AMD CPU/C++ GCC4.7.2/Codeblocks

详细描述：如下所示”代码块1“,每次在调用encrypt()函数时均会申请一次内存，如何在析构函数中一次性销毁所有产生的内存，”代码块2“的方法不符合要求

扩展：如果上述问题无较好答案，是否有其他方法可以避免在类函数中使用new，但也能达到目的
代码块1：

#include <iostream>
#include <string.h>
using namespace std;
class cipher
{
public:
    char key[128];
    cipher(const char *key_)
    {
        strcpy(key,key_);
    }



    char* encrypt(const char* text)
    {
        int a= (int((strlen(text)/128)+1))*128;
        //每运行一次则产生一个新内存
        char *tempResult=new char[a];
        strcpy(tempResult,text);
        strcat(tempResult,key);

        return tempResult;
    }


    ~cipher()
    {

    }

};

int main()
{
    const char* myKey="this is a key";
    cipher encryptBook(myKey);

    const char* engilishBookContent="this is the content of the English book.";
    cout<<encryptBook.encrypt(engilishBookContent)<<endl;

    const char* chineseBookContent="this is the content of the Chinese book.";
    cout<<encryptBook.encrypt(chineseBookContent)<<endl;
}

代码块2：

 class cipher
{
public:
    char key[128];
    char *tempResult;
    cipher(const char *key_)
    {
        strcpy(key,key_);
        tempResult = null;
    }

    char* encrypt(const char* text)
    {
        int a= (int((strlen(text)/128)+1))*128;
       if(tempResult != null){delete [] tempResult ;tempResult = null;}
       tempResult=new char[a];
        strcpy(tempResult,text);
        strcat(tempResult,key);

        return tempResult;
    }

    ~cipher()
    {
       if(tempResult != null){delete [] tempResult ;tempResult = null;}
    }

};

Answer 1

 #include <iostream>
#include <string.h>
using namespace std;
class cipher
{
public:
    char key[128];
    cipher(const char *key_)
    {
        strcpy(key,key_);
        recordNew=NULL;//初始化指针数组
        qtyRecord=0;//初始化指针数组的元素个数

    }


    char* encrypt(const char* text)
    {
        int a= (int((strlen(text)/128)+1))*128;
        char *tempResult=new char[a];
        strcpy(tempResult,text);
        strcat(tempResult,key);
        record(tempResult);
        return tempResult;
    }


    void record(char *newChar)
    {
        cout<<"newChar=0X"<<hex<<(int)newChar<<endl;
        char **tempP=new char* [qtyRecord+1];

        //如果是第一次调用encrypt()函数，则直接赋值
        //如果不是则需要先拷贝原指针成员后，再添加新建的指针
        if (recordNew==NULL)
            tempP[0]=newChar;
        else
        {
            for (int i=0; i<=qtyRecord-1; ++i)
            {
                tempP[i]=recordNew[i];
                cout<<"i="<<i<<"  "<<"recordNew["<<i<<"]="<<hex<<(int)recordNew[i]<<endl;
            }

            tempP[qtyRecord]=newChar;
            delete[] recordNew;//删除老的recordNew指针数组
        }

        recordNew=new char*[qtyRecord+1];

        for(int j=0; j!=qtyRecord+1; ++j)
        {
            recordNew[j]=tempP[j];
            cout<<"recordNew["<<j<<"]="<<"0x"<<hex<<(int)recordNew[j]<<endl;
        }

        ++qtyRecord;//计数器加1
        delete[] tempP;//删除临时指针数组
        cout<<"****************************"<<endl;
    }

    ~cipher()
    {
        if (recordNew==NULL) return;
        delete[] recordNew;
    }
//private:
    char** recordNew;
    int qtyRecord;


};

int main()
{
    const char* myKey="this is a key";
    cipher encryptBook(myKey);

    const char* engilishBookContent="this is the content of the English book.";
    encryptBook.encrypt(engilishBookContent);
//    cout<<encryptBook.encrypt(engilishBookContent)<<endl;

    const char* chineseBookContent="this is the content of the Chinese book.";
    encryptBook.encrypt(chineseBookContent);
//    cout<<encryptBook.encrypt(chineseBookContent)<<endl;

    const char* mathBookContent="this is the content of the math book.";
    encryptBook.encrypt(mathBookContent);
//    cout<<encryptBook.encrypt(mathBookContent)<<endl;

    const char* historyBookContent="this is the content of the history book.";
    encryptBook.encrypt(historyBookContent);
//    cout<<encryptBook.encrypt(historyBookContent)<<endl;

    cout<<"++++++++++++++++++++++++++++"<<endl;
    cout<<encryptBook.recordNew[1]<<endl;
    encryptBook.~cipher();
    cout<<encryptBook.recordNew[1]<<endl;
}