ANSI C K&R Exercise: Print [o]ne [w]ord per [l]ine – pretty easy.

1-12.c

/* *
 * From: C Answer Book
 *  Clovis L. Tondo
 *  Scott E. Gimpel
 * ISBN: 7-302-02728-5
 * */
#include <stdio.h>

#define IN   1   /* inside word  */
#define OUT  0   /* outside word */

/* print input one word per line */
main()
{
  int c, state;
  
  state = OUT;
  while((c = getchar()) != EOF) {
    if (c == ' ' || c == '\n' || c == '\t') {
      if (state == OUT) {
        putchar('\n');    /* finish the word */
        state = OUT;
      }
    }
  } else if (state == OUT) {
      state = IN;   /* begining of word */
      putchar(c);
  } else {
      putchar(c);   /* inside the word */
  }
}

owl.c

/* *
 * Exercise 1-12. Write a program that prints its input one word per line.
 * */

#include <stdio.h>
#define IS_UPPER(N) ((N) >= 'A' && (N) <= 'Z')   /* 'A'==65 && 'Z'==90 */
#define IS_LOWER(N) ((N) >= 'a' && (N) <= 'z')   /* 'a'==97 && 'z'==122 */
#define IS_ALPHA(N) (IS_LOWER(N) || IS_UPPER(N)) /* [A-Za-z] x*/
#define OUT 0
#define IN  1
int main(void)
{
  int c = EOF, state = OUT;
  while ((c = getchar()) != EOF) {
    if (IS_ALPHA(c)) {
      state = IN;
      putchar(c);
    }
    else if (state == IN) {
      state = OUT;
      putchar('\n');
    }
  }

  return 0;
}