c - 为指向二维数组指针的指针赋值

Question

我相信我的声明不正确。我有一个 2D 数组和一个 3D 数组。我出现了段错误，因为我将值 0 或 NULL 分配给其中一个数组。我知道这是试图将地址 NULL 分配给无效的指针。

也许我需要在分配之前取消引用数组？如果是这样，我该怎么做？如果没有，我需要如何声明数组？

double **WeightIH = calloc(51*20,sizeof(double **));
double ***Input = calloc(51*40, sizeof(double ***));
DeltaWeightIH[i][j] = 0.0 ;

Answer 1

最简单的方法是使用 for 循环。就像下面的例子

int i, j = 0;
int rows = 5;
int cols = 2;

int rows2 = 3; // for 3d array

double  **arr2d = (double  **)calloc(rows, sizeof(double));
double  ***arr3d = (double  ***)calloc(rows, sizeof(double));
for (i = 0; i < rows; j++)
{
    arr2d[i] = (double *)calloc(cols, sizeof(double));
}

arr2d[1][2] = 0.0; //Or *(*(arr2d+1)+2) = 0.0;

//the same thing for 3d it just need another for loop.
for (i = 0; i < rows; j++)
{
    arr3d[i] = (double **)calloc(cols, sizeof(double));
    for (j = 0; i < cols; j++)
    {
        arr3d[i][j] = (double *)calloc(rows2, sizeof(double));
    }
}

arr3d[1][2][1] = 0.0; //Or *(*(*(arr2d+1)+2)+1) = 0.0;