LiangXu Wang

二维数组new小结
转至水木清华
1.

    A (*ga)[n] = new A[m][n];
    ...
    delete []ga;

缺点：n必须是已知
优点：调用直观，连续储存，程序简洁(经过测试，析构函数能正确调用)

2.

A** ga = new A*[m];
    for(int i = 0; i < m; i++)
        ga[i] = new A[n];
    ...
    for(int i = 0; i < m; i++)
        delete []ga[i];
    delete []ga;

缺点：非连续储存，程序烦琐，ga为A**类型
优点：调用直观，n可以不是已知

3.

 A* ga = new A[m*n];
    ...
    delete []ga;

缺点：调用不够直观
优点：连续储存，n可以不是已知

4.

vector > ga;
    ga.resize(m);                       //这三行可用可不用
    for(int i = 1; i < n; i++)          //
        ga[i].resize(n);                //
    ...

缺点：非连续储存，调试不够方便，编译速度下降，程序膨胀(实际速度差别不大)
优点：调用直观，自动析构与释放内存，可以调用stl相关函数，动态增长

5.

 vector ga;
    ga.resize(m*n);

   A** ga = new A*[m];
    ga[0] = new A[m*n];
    for(int i = 1; i < m; i++)
        ga[i] = ga[i-1]+n;
    ...
    delete [] ga[0];
    delete [] ga;