/* echowords.c
 *
 * Neal Nelson 2009.10.05
 *
 * Echo command and argument words on subsequent lines
 * Allocate each word in getArg. Shows passing modifiable pointer parameters,
 *   but the allocation of all words on a line should be encapsulated.
 */
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#define MAXLINE 81

/* Prototypes */
char *getArg(char *buf, char **word);

main()
{ char buf[MAXLINE];
  char *p, *word;

  while (fgets(buf, MAXLINE, stdin) != NULL )
  { for (p = buf; (p = getArg(p,&word)) != NULL; ) /* last pass is just sp+nl */
    { printf ("  %s\n", word);
    }
  }
}

/* buf is the incomming string, word is the address of a return string */
char* getArg(char *buf, char **word)
{ char *p;
  int len;
  char ws[] = " \n\t\r\f\v";

  p = buf + strspn(buf,ws);                 /* skip leading spaces */
  len = strcspn(p,ws);
  if (len != 0)                             /* get next word */
  { *word = (char *)malloc(len+1);
    strncpy(*word,p,len);
    *(*word+len) = '\0';
    return p+len;
  } 
  else return NULL;
}