diplodocus.org Git - nmh/blob - docs/historical/mh-6.8.5/miscellany/mem/getopt.c

   1 #include <stdio.h>
   2
   3 /*
   4  * get option letter from argument vector
   5  */
   6 int     opterr = 1,             /* useless, never set or used */
   7         optind = 1,             /* index into parent argv vector */
   8         optopt;                 /* character checked for validity */
   9 char    *optarg;                /* argument associated with option */
  10
  11 #define BADCH   (int)'?'
  12 #define EMSG    ""
  13 #define tell(s) fputs(*nargv,stderr);fputs(s,stderr); \
  14                 fputc(optopt,stderr);fputc('\n',stderr);return(BADCH);
  15
  16 getopt(nargc,nargv,ostr)
  17 int     nargc;
  18 char    **nargv,
  19         *ostr;
  20 {
  21         static char     *place = EMSG;  /* option letter processing */
  22         register char   *oli;           /* option letter list index */
  23         char    *index();
  24
  25         if(!*place) {                   /* update scanning pointer */
  26                 if(optind >= nargc || *(place = nargv[optind]) != '-' || !*++place) return(EOF);
  27                 if (*place == '-') {    /* found "--" */
  28                         ++optind;
  29                         return(EOF);
  30                 }
  31         }                               /* option letter okay? */
  32         if ((optopt = (int)*place++) == (int)':' || !(oli = index(ostr,optopt))) {
  33                 if(!*place) ++optind;
  34                 tell(": illegal option -- ");
  35         }
  36         if (*++oli != ':') {            /* don't need argument */
  37                 optarg = NULL;
  38                 if (!*place) ++optind;
  39         }
  40         else {                          /* need an argument */
  41                 if (*place) optarg = place;     /* no white space */
  42                 else if (nargc <= ++optind) {   /* no arg */
  43                         place = EMSG;
  44                         tell(": option requires an argument -- ");
  45                 }
  46                 else optarg = nargv[optind];    /* white space */
  47                 place = EMSG;
  48                 ++optind;
  49         }
  50         return(optopt);                 /* dump back option letter */
  51 }