One Dimensional Array
int *myarray = malloc(no_of_elements * sizeof(int));
//Access elements as myarray[i]
2 Dimensional Array
Method1
int **myarray = (int **)malloc(nrows * sizeof(int *));
for(i = 0; i < nrows; i++)
{
myarray[i] = malloc(ncolumns * sizeof(int));
//allocating 1 D array = number of elements in column
}
// Access elements as myarray[i][j]
Method 2 (Contagious Allocation)
int **myarray = (int **)malloc(nrows * sizeof(int *));
myarray[0] = malloc(nrows * ncolumns * sizeof(int));
for(i = 1; i < no_of_rows; i++)
myarray[i] = myarray[0] + (i * ncolumns);
// Access elements as myarray[i][j]
In either case, the elements of the dynamic array can be accessed with normal-looking array subscripts:
array[i][j]
. Method 3
int *myarray = malloc(nrows * ncolumns * sizeof(int));
// Access elements using myarray[i * ncolumns + j].
i.e. you must now perform subscript calculations manually, accessing the i,jth element with
array3[i * ncolumns + j]
. (A macro can hide the explicit calculation, but invoking it then requires parentheses and commas which don't look exactly like multidimensional array subscripts.) Method4
Finally, you can use pointers-to-arrays:
int (*array4)[NCOLUMNS] =
(int (*)[NCOLUMNS])malloc(nrows * sizeof(*array4));
, but the syntax gets horrific and all but one dimension must be known at compile time.
Three Dimensional Array
#define MAXX 3
#define MAXY 4
#define MAXZ 5
main()
{
int ***p,i,j;
p=(int ***) malloc(MAXX * sizeof(int ***));
for(i=0;i
{
p[i]=(int **)malloc(MAXY * sizeof(int *));
for(j=0;j
p[i][j]=(int *)malloc(MAXZ * sizeof(int));
//allocating 1D array of size = size of last dimensional...So we have to allocate
//n1*n2 such arrays...where n1 and n2 are 2 such dimensional.
}
for(k=0;k
for(i=0;i
for(j=0;j
p[i][j][k]=;
}
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