指针的指针的指针的用法范例

//一个小函数，精巧之处在于只分配两次内存，用下标计算完成行列转换
#include <iostream>
using namespace std;

template<class T>
void get2array(T ***ptr, int row, int column)
{
    *ptr=new T *[row];
    (*ptr)[0]=new T[row*column];
    for(int i=1;i<row; ++i)
        (*ptr)[i]=(*ptr)[i-1]+column;
}

int main()
{
    int row = 8;
    int column = 10;
    int **ptr;
    get2array(&ptr,row,column);
    for(int i=0;i<row;++i)
    {
        for(int j=0;j<column;++j)
        {
            ptr[i][j] = i*column + j;
            std::cout << ptr[i][j] << " ";
        }
        std::cout << '\n';
    }
    std::cout << "行列转换" << std::endl;
    for(int i=0;i<column;++i)
    {
        for(int j=0;j<row;++j)
        {
            std::cout << ptr[j][i] << " ";
        }
        std::cout << '\n';
    }
    delete []ptr[0];
    delete []ptr;
    return 0;
}