二维数组动态分配

代码转自：http://blog.youkuaiyun.com/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.youkuaiyun.com/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.youkuaiyun.com/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;  
}