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

# include "vector.h"

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

void vector ( int *x_in, int *x_out )

/******************************************************************************/
/*
  Purpose:

    vector() stores, saves, and returns a vector x of 3 entries.

  Discussion:

    vector ( x_in, NULL )
      copies the values in x_in into the internal vector x_default.

    vector ( NULL, x_out )
      copies the values in x_default into the output vector x_out.

    vector ( x_in, x_out )
      copies the values in x_in into the internal vector x_default,
      and returns these same value in the output vector x_out.

    vector ( NULL, NULL )
      prints the values in x_default.

  Licensing:

    This code is distributed under the MIT license.

  Modified:

    11 October 2025

  Author:

    John Burkardt

  Input:

    int *X_IN: NULL or the address of X.

  Output:

    int *X_OUT: the current value of X.

  Local:

    int *X_DEFAULT: the internal value of X.

*/
{
  int i;
  static int x_default[3] = { 1, 2, 3 };
/*
  New values, if supplied on input, overwrite the current values.
*/
  if ( x_in )
  {
    for ( i = 0; i < 3; i++ )
    {
      x_default[i] = x_in[i];
    }
  }
/*
  The current values are copied to the output.
*/
  if ( x_out )
  {
    for ( i = 0; i < 3; i++ )
    {
      x_out[i] = x_default[i];
    }
  }
/*
  As a check, print current items.
  In practice, this code would do its work silently.
*/
  if ( x_in )
  {
    printf ( "  x_in = (%d,%d,%d)\n", x_in[0], x_in[1], x_in[2] );
  }
  else
  {
    printf ( "  x_in = NULL\n" );
  }

  if ( x_out )
  {
    printf ( "  x_out = (%d,%d,%d)\n", x_out[0], x_out[1], x_out[2] );
  }
  else
  {
    printf ( "  x_out = NULL\n" );
  }

  printf ( "  x_default = (%d,%d,%d)\n", x_default[0], x_default[1], x_default[2] );

  return;
}