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Hi!
Can any body expalin me the way of allocating memory for a two dimensional array. I mean i will have a pointer(or double pointer) but i should allocate memory using malloc or calloc. When i am accesing data i should follow array indexing like a[1][2];
One of the ways to allocate memory for a double pointer is given in the code below,
Code:
// m is the no. of rows
// n is the no. of columns
int **matrix;
matrix = (int **) malloc(sizeof(int*)*m);
for(i=0;i<m;i++)
{
matrix[i] = (int *) malloc(sizeof(int) * n);
}
depending on what you want to do with the array a double pointer approach is not always the best, because if the array is nXm then each traversal requires n pointer dereferences where each may require a cache refill(if array is big), the amount of memory required to store the array is m*(n+1) if the datasize is the same as pointer size, however, substituting one row for another is no more than a single memory assignment. my preferred method is to create a 1d array m*n in size and access it like array(i,j)=array[i+j*n], traversal is much quicker and it takes less memory but row operations are much more difficult.
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