#include <stdio.h>

/* hasNeg:
 * Given a vector v and integer n,
 * return whether or not one of its first n elements is negative.
 * (We assume v has at least n elements.)
 */
bool hasNeg( int v[], int n ) {
  if (n == 0)
    return false;
  else {
    if (v[n-1] < 0)
      return true;
    else
      return hasNeg( v, n-1 );
    }
  } 

/* main:
 * create a vector, fill it with values, then call hasNeg.
 */
int main() {
  const int vSize = 10;

  int vec[ vSize ];
  int i = 0;
  while ( i < vSize ) {
    vec[ i ] = (i - 4) * (i - 7);
    i = i + 1; 
    }

  if (hasNeg( vec, vSize ))
    printf( "Some element of vec is negative.\n" );
  else
    printf( "No element of vec is negative.\n" );

  return 0;
  }



 

/* -----------
   Although hasNeg's loop is written and indented logically,
   it looks awful, all those nested-ifs.
   Here is the more conventional way of indenting nested-ifs:

  if (n == 0)
    return false;
  else if (v[n-1] < 0)
    return true;
  else
    return hasNeg( v, n-1 );
*/

/* --------------

Note that you can get yourself into trouble easily
whenever the first branch of an if statment is another if:

  if (n==0)
    if (m == 0)
      return false;
// how to indent these next two lines?:
// else
//  return false;
 
(It turns out, the rule is to match the else with the *nearest*
unmatched if.)
*/