2D array chunking in C

Question

How do I subdivide a large 2D array into smaller 2D arrays which are arranged in row-major order?

Answer 1

/*********************************

splitting 2D array of size M by N

into slices of size A by B

******************************************/

#include <stdio.h>

#define M (25)

#define N (25)

#define A (4)

#define B (3)

GO()

{

int a[M][N];

int slice[A][B];

int _M = M;

int _N = N;

int _A = A;

int _B = B;

for (int iLoop=0; iLoop<M; iLoop++)

{

for (int jLoop=0; jLoop<N; jLoop++)

{

a[iLoop][jLoop] = iLoop*N + jLoop;

//printf("%d ",a[iLoop][jLoop]);

}

//printf("\n");

}

//****************************************************************

int numRowSlices = _M/_A;

int remainderRowSlices = _M % _A;

int numColumnSlices = _N/_B;

int remainderColumnSlices = _N % _B;

int rowMajor=0;

int columnLoop=0;

for (rowMajor=0; rowMajor+_A<_M; rowMajor+= _A)

{

for (columnLoop=0; columnLoop<_N; columnLoop+=_B)

{

printf(" top left corner : %d %d \n",rowMajor,columnLoop);

}

for (int iColumnLoop=columnLoop+1; iColumnLoop<_N; iColumnLoop++)

{

printf(" top left corner : %d %d \n",rowMajor,iColumnLoop+columnLoop);

}

}

printf(" REMAINING ROWS ....\n");

for (int iRowLoop=rowMajor; iRowLoop<_M; iRowLoop++)

{

for (columnLoop=0; columnLoop<_N; columnLoop+=_B)

{

printf(" top left corner : %d %d \n",iRowLoop,columnLoop);

}

for (int iColumnLoop=columnLoop+1; iColumnLoop<_N; iColumnLoop++)

{

printf(" top left corner : %d %d \n",iRowLoop,iColumnLoop+columnLoop);

}

}

}

int main()

{

GO();

}