问题
So I have a program with a struct
typedef struct s_struct {
int rows;
int cols;
char* two_d; //This is supposed to be the 2D array
} *GRID;
I want to create a struck and dynamically allocate memory to it and then fill the 2D array but I don't know how. Here is what I have for the create(int prows, int pcols) function:
GRID grid = malloc(sizeof(struct s_struct));
grid ->rows = prows;
grid ->cols = pcols;
grid ->two_d = malloc(sizeof(char) * (rows*cols));
I don't understand how this creates a 2D array if it even does and how I can go about filling the array.
回答1:
this line:
grid ->two_d = malloc(sizeof(char) * (rows*cols));
allocates a 'continuous in memory' grid/matrix that can be referenced by:
grid[row_offset][cols_offset]
where the 'row_offset' can be 0...(row-1)
where the 'cols_offset' can be 0...(cols-1)
note: 'sizeof(char)' is always 1,
so including that phrase
in the malloc parameter just clutters the code
because '(1*something)' is always 'something'
as the 1 has no effect.
suggest: remove the 'sizeof(char)' from the malloc parameter
来源：https://stackoverflow.com/questions/29689611/how-can-i-have-a-dynamically-allocated-2d-array-in-c