/* argv.c
 *
 * Neal Nelson 2009.10.05
 *
 * Construct a NULL terminated argv array of strings from an input line.
 */

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

#define MAXLINE 81
#define MAXARGV 5

/* Prototypes */
char **mkargv(char *buf);

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

  printf("mkArgv: enter words on a line, ^d to quit\n>");
  while (fgets(buf, MAXLINE, stdin) != NULL )
  { argv = mkargv(buf);
    printf("Contents of argv string array:\n");
    for (p = argv; *p != NULL; p++) printf("  %s\n",*p);
    printf(">");
  }
  printf("\n");
}

char **mkargv(char *buf)
{ char *p;
  char **argv, **argvp;
  int len, argc;
  char ws[] = " \n\t\r\f\v";

  argv = (char **)malloc(( MAXARGV+1)*sizeof(char **) );
  for (p = buf, argvp=argv, argc = 0; *p != '\0' && argc < MAXARGV; )
  { p = p + strspn(p,ws);                     /* skip leading spaces */
    len = strcspn(p,ws);
    if (len != 0)                             /* get next word */
    { *argvp = (char *)malloc( (len+1)*sizeof(char *) );
      strncpy(*argvp,p,len);
      *(*argvp + len) = '\0';
      argvp++;
      argc++;
      p = p+len;
    } 
  }
  *(argvp) = (char *)NULL;                     /* end of string array */
  return argv;
}