二维数组动态分配

àì夳堔傛蜴生んèń 2022-07-16 11:48 201阅读 0赞

代码转自：http://blog.csdn.net/lifanxi/article/details/1649840

#include <iostream>
    #include <cstdlib>
    #include <new>
    
    template <typename T>
    T **darray_new(int row, int col)
    {
        int size = sizeof(T);
        void **arr = (void **) malloc(sizeof(void *) * row + size * row * col);
        if (arr != NULL)
        {
            unsigned char * head;
            head = (unsigned char *) arr + sizeof(void *) * row;
            for (int i = 0; i < row; ++i)
            {
                arr[i] =  head + size * i * col;
                for (int j = 0; j < col; ++j)
                    new (head + size * (i * col + j)) T;
            }
        }
        return (T**) arr;
    }
    
    template <typename T>
    void darray_free(T **arr, int row, int col)
    {
        for (int i = 0; i < row; ++i)
            for (int j = 0; j < col; ++j)
                arr[i][j].~T();
        if (arr != NULL)
            free((void **)arr);
    }

代码转自：http://blog.csdn.net/MoreWindows/article/details/7664479

//C++语言中动态的申请二维数组 new delete  
    #include <new>  
    #include <cstdio>  
    #include <cstdlib>  
    #include <string>  
    using namespace std;  
    //动态申请二维数组  
    template <typename T>  
    T** new_Array2D(int row, int col)  
    {  
        int size = sizeof(T);  
        int point_size = sizeof(T*);  
        //先申请内存，其中sizeof(T*) * row表示存放row个行指针  
        T **arr = (T **) malloc(point_size * row + size * row * col);  
        if (arr != NULL)  
        {     
            T *head = (T*)((int)arr + point_size * row);  
            for (int i = 0; i < row; ++i)  
            {  
                arr[i] =  (T*)((int)head + i * col * size);  
                for (int j = 0; j < col; ++j)  
                    new (&arr[i][j]) T;  
            }  
        }  
        return (T**)arr;  
    }  
    //释放二维数组  
    template <typename T>  
    void delete_Array2D(T **arr, int row, int col)  
    {  
        for (int i = 0; i < row; ++i)  
            for (int j = 0; j < col; ++j)  
                arr[i][j].~T();  
        if (arr != NULL)  
            free((void**)arr);  
    }  
    int main()  
    {  
        printf("  C++语言中动态的申请二维数组 new delete\n");    
        printf(" -- by MoreWindows( http://blog.csdn.net/MoreWindows ) --\n\n");  
      
        printf("请输入行列(以空格分开): ");  
        int nRow, nCol;  
        scanf("%d %d", &nRow, &nCol);  
      
        //动态申请连续的二维数组  
        string **p = new_Array2D<string>(nRow, nCol);  
      
        //为二维数组赋值  
        int i, j;  
        for (i = 0; i < nRow; i++)  
            for (j = 0; j < nCol; j++)  
            {  
                char szTemp[30];  
                sprintf(szTemp, "(第%d行,第%d列)", i, j);  
                p[i][j] = szTemp;  
            }  
      
        //输出二维数组      
        for (i = 0; i < nRow; i++)  
        {  
            for (j = 0; j < nCol; j++)  
                printf("%s ", p[i][j].c_str());  
            putchar('\n');  
        }  
      
        delete_Array2D<string>(p, nRow, nCol);  
        return 0;  
    }