"If builders made buildings the way programmers write
programs, then the first woodpecker to come along would
destroy civilization." -Weinberg''s Law
How do I allocate a multidimensional array with new?
Author
All I need is a dynamically allocated 3d array.
Can someone tell me how to do this.
I''ve tried:
int ***array = new int[10][10][10];
No luck there. I can''t find any examples
in the msdn library.
d e e p s k y . s 5 . c o m
"If builders made buildings the way programmers write
programs, then the first woodpecker to come along would
destroy civilization." -Weinberg''s Law
"If builders made buildings the way programmers write
programs, then the first woodpecker to come along would
destroy civilization." -Weinberg''s Law
int size1 = 10;int size2 = 10;int size3 = 10;int ***threeDarray;threeDarray = (int***)malloc(sizeof(int**)*size1);for(int a = 0; a < 10; a++){ threeDarray[a] = (int**)malloc(sizeof(int*)*size2); for(int b = 0; b < 10; b++){ threeDarray[a][b] = (int*)malloc(sizeof(int)*size3); }}
Author
ugh! what a pain in the ass. I''d rather just do a 1D
with:
int *array = new int[length * width * height];
I just didn''t want any multiplies slowing my indexing
down.
There has to be a better way.
d e e p s k y . s 5 . c o m
"Who is General Failure and why is he reading my disk?"
with:
int *array = new int[length * width * height];
I just didn''t want any multiplies slowing my indexing
down.
There has to be a better way.
d e e p s k y . s 5 . c o m
"Who is General Failure and why is he reading my disk?"
Oops, you wanted to use the new operator. Malloc is just so ingrained in my head its not funny.
You do realize that the compiler should change the 3D array into a single array in its optimizations. If you write it as a 1D array, it might save a little time, but not much.
xxx = new int**[size1];for(int b = 0; b < 10; b++){ xxx[b] = new int*[size2]; for(int c = 0; c < 10; c++) { xxx[b][c] = new int[size3]; }} You do realize that the compiler should change the 3D array into a single array in its optimizations. If you write it as a 1D array, it might save a little time, but not much.
quote:Original post by atreyu
I just didn''t want any multiplies slowing my indexing
down.
The compiler will implicitly do multiplies in multi-dimensional arrays. To do them explicitly shouldn''t slow you down.
Mike
quote:Original post by VetinariOriginal post by atreyu
I just didn''t want any multiplies slowing my indexing
down.
The compiler will implicitly do multiplies in multi-dimensional arrays. To do them explicitly shouldn''t slow you down.
Mike
I think that depends on the type of array. It could not possibly use multiplication for the [][][] type because it is not one solid block of mememory, it is an array of arrays of ints. On the other hand I think there is a [,,] type which would use multiplies.
or:
int (*array)[10][10];
array = new int[10][10][10];
This is the second time this question has been answered in as many weeks--should definitely go in the FAQ (when we get one).
int (*array)[10][10];
array = new int[10][10][10];
This is the second time this question has been answered in as many weeks--should definitely go in the FAQ (when we get one).
quote:Original post by Anonymous Poster
I think that depends on the type of array. It could not possibly use multiplication for the [][][] type because it is not one solid block of mememory, it is an array of arrays of ints. On the other hand I think there is a [,,] type which would use multiplies.
Just to be clear, statically allocated multidimensional arrays are one continuous block of memory, and implicit multiplies are used.
Mike
This topic is closed to new replies.
Advertisement
Popular Topics
Advertisement
