getopt.c

asn格式文件的编译器

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

char* optarg;
int optind=1;

  /// Callers store zero here to inhibit the error message for
  /// unrecognized options.
int opterr;
char *nextchar_;
  
int getopt(int argc_, char** argv_, const char* optstring_) 
{
  int opt; // Character checked for validity.
  const char *oli; // Option letter index.
  if (argv_ == 0)
    {
      // It can happen, e.g., on VxWorks.
      optind = 0;
      return -1;
    }


  if (nextchar_ == 0 || *nextchar_ == '\0')
    {
      // Update scanning pointer.

      if (optind >= argc_
	  || *(nextchar_ = argv_[optind]) != '-')
	{
	  nextchar_ = "";
	  return -1;
	}

      if (nextchar_[1] != 0
	  && *++nextchar_ == '-')
	{
	  // Found "--".
	  ++optind;
	  nextchar_ = "";
	  return -1;
	}
    }

  // Option letter okay?
  opt = (int) *nextchar_++;

  if (opt == (int) ':'
      || ((oli = strchr (optstring_, opt)) == 0))
    {
      // If the user didn't specify '-' as an option, assume it means
      // -1.
      if (opt == (int) '-')
	return -1;

      if (*nextchar_ == 0)
	++optind;

      if (opterr && *optstring_ != ':')
		fprintf(stderr,"%s: illegal option -- %c\n",argv_[0],opt);
      return '?';
    }

  if (*++oli != ':')
    { // Don't need argument.
      optarg = 0;
      if (!*nextchar_)
	++optind;
    }
  else
    { // Need an argument.
      if (*nextchar_) // No white space.
	optarg = nextchar_;
      else if (argc_ <= ++optind)
	{
	  // No arg.
	  nextchar_ = "";

	  if (*optstring_ == ':')
	    return ':';
	  if (opterr)
	    fprintf(stderr, "%s: option requires an argument -- %c\n",argv_[0], opt);
	  return '?';
	}
      else // White space.
	optarg = argv_[optind];

      nextchar_ = "";
      ++optind;
    }

  return opt; // Dump back option letter.
}