Answer 2D1

#include <stdio.h>
#include <stdlib.h>

/* Puzzle DD01 -- fill an N by M integer array with ascending values and print them out. */

int main()
{
  const int Nrows = 3, Mcols = 5 ;
  int x[Nrows][Mcols] ;
  
  int count = 0; /* Values to copy to the array */
  
  int r, c;  /* row and column indexes for the array */
  
  /* Fill the array with ascending integers */
  for ( r=0; r<Nrows; r++ )
    for ( c=0; c<Mcols; c++ )
      x[r][c] = count++ ;
    
  /* Print out the array */
  for ( r=0; r<Nrows; r++ )
  {
    for ( c=0; c<Mcols; c++ )
      printf("%2d ", x[r][c] );
    printf("\n");  
  }
  
  printf("\n");
  return 0;
}

Here is a version for compilers that compain about variable array dimensions:

#include <stdio.h>
#include <stdlib.h>

#define Nrows 10
#define Ncols 15
int x[Nrows][Mcols] ;

/* Puzzle DD01 -- fill an N by M integer array with ascending values and print them out. */

int main()
{
  int count = 0; /* Values to copy to the array */
  int r, c;  /* row and column indexes for the array */
  
  /* Fill the array with ascending integers */
  for ( r=0; r<Nrows; r++ )
    for ( c=0; c<Mcols; c++ )
      x[r][c] = count++ ;
    
  /* Print out the array */
  for ( r=0; r<Nrows; r++ )
  {
    for ( c=0; c<Mcols; c++ )
      printf("%2d ", x[r][c] );
    printf("\n");  
  }
  
  printf("\n");
  return 0;
}