function swap_array(int **after, int **before) {
int **temp = after;
after = before;
before = temp;
 
}

#include <stdio.h>
 
void swap( int rows, int cols, float (**after)[rows][cols] , 
           float (**before)[rows][cols] )
{
  float (*temp)[rows][cols] = *after ;
  *after = *before ;
  *before = temp ;
}
 
int main()
{
  int rows = 3, cols = 4 ;
  float one[rows][cols] ; one[0][0] = 1.1 ;
  float two[rows][cols] ; two[0][0] = 2.2 ;
  float (*p1)[rows][cols] = &one ; 
  float (*p2)[rows][cols] = &two ; 
  printf( "%f\t%f\n", (*p1)[0][0], (*p2)[0][0] ) ; 
  swap( rows, cols, &p1, &p2 ) ;
  printf( "%f\t%f\n", (*p1)[0][0], (*p2)[0][0] ) ; 
}

void array_function( int rows, int cols, float (*after)[rows][cols],
                     float (*before)[rows][cols] )
{
	//for some iterations	
	for(;;)
	{
		int i, j ;
		//for all the elements int the array
		for (i=1; i<rows; i++)
			for(j=1; j<cols; j++)
				(*after)[i][j] = 4 * (*before)[i][j] ;
 
		//afterwards prepare for the next iteration
		swap( rows, cols, &after, &before ) ;
	}
}

void array_function(int rows, int cols, float after[rows][cols] , float before[rows][cols])
  {
  ...
  }
 
int main()
  {
  int n = 5;
  int m = 6;
 
  int before[n][m];
  int after[n][m];
 
  array_function( 5, 6, before, after );  // this works
  array_function( 5, 6, after, before );  // this works
 
  ...
  }