Linux Programming by Exemple(第二章参数、选项..

时间：2006-04-11 来源：gameboytxt

课后练习： 1。假设程序接受选项-a、-b和 -c，并且-b 需要参数。请为这个程序写一段手工解析参数的代码，不能使用getopt()或者getopt_long()，接收到-- 结束选项处理。确保-ab、 -bYANKEES、-b YANKEES 和-abYANKEES都能运行。测试你的程序。 --------------------CODE------------------------- /* exer-01.c
    author: gameboytxt
    2006.3
*/

#include <stdio.h>

int aflg,bflg,cflg;             /* a, b ,c选项的标记变量 */
char* optarg;                  /*保存选项参数*/

main( argc, argv )
int argc;
char* argv[];
{

     if ( --argc > 0 && *argv[1] == '-' ) {
        argv++;
        while ( *++*argv )      switch( **argv ) {

             case 'a' :
                 aflg++;
                 continue;

             case 'b' :
                 bflg++;

              if (*++*argv){
                 optarg=*argv;
                 goto display_opt;
                }
              else if (--argc ==0){
                  printf("b option require argument\n");
                  return -1;
              }else {

                  optarg=*++argv;
                  goto display_opt;
             }



             case 'c' :
                 cflg++;
                 continue;
             case '-':
                 goto display_opt;

             default :
              continue;

            }

    }

    display_opt : {
         if (aflg) printf ( "This is -a option\n");
         if (bflg) printf ( "This is -b option\nits argument is %s\n", optarg);
         if (cflg) printf ("This is -c option\n");
    }
        return 0;

} -----------------END CODE-------------------------- 2。实现getop()。第一个版本不用担心'optstring[0]==':'' 的情况，也可以忽略 opterr。 3。在你的getopt()中增加处理'optstring[0]==':''和opterr的代码。 ----------------CODE------------------------------- #include <stdio.h>
char *optarg = NULL; //如果选项接受参数的话，那么它就是选项参数。
int optind = 1;       //argv的当前索引。
int opterr = 1;       //当它为零，getopt为无效选项，和缺少选项参数。
int optopt = '?';     //当发现无效字符的时候，getopt或者返回‘？’或者返回‘：’
                      //并且optopt包含了所发现的无效选项字符。
static char *
my_index (str, chr)
     const char *str;
     int chr;
{
while (*str)
    {
      if (*str == chr)
return (char *) str;
      str++;
    }
return 0;
} int getopt (int argc, char *const argv[], const char *optstring){
    static char *nextchar = NULL;     if (optind != argc && !strcmp (argv[optind], "--"))
     optind = argc;

if (optind == argc)
{
       return -1;
}

    if (nextchar == NULL || *nextchar == '\0') {
        if ( argv[optind][0] != '-' || argv[optind][1] == '\0' ){
        optarg = argv[optind++];
     return 1;
    }
     nextchar = (argv[optind] + 1
    + (argv[optind][1] == '-'));
}

char c = *nextchar++;
    char *temp = my_index (optstring, c);     if ( *nextchar == '\0' )
      ++optind;
    if ( temp == NULL || c == ':' )
    {
      if (opterr)
      {
          printf ("%s: invalid option -- %c\n",
         argv[0], c);
   }
optopt = c;
return '?';
    }
    if (temp[1] == ':')
    {
        if (temp[2] == ':')
        {
            if (*nextchar != '\0')
         {
         optarg = nextchar;
         optind++;
          }
     else
       optarg = NULL;
       nextchar = NULL;
     }
else
   {
       if (*nextchar != '\0')
       {
  optarg = nextchar;

  optind++;
       }
    else if (optind == argc)
        {
            if (opterr)
      {
               printf ("%s: option requires an argument -- %c\n",
      argv[0], c);
       }
  optopt = c;
  if (optstring[0] == ':')
    c = ':';
  else
    c = '?';
        }
    else
       optarg = argv[optind++];
       nextchar = NULL;
   }    }
    return c;
     }

            int main( int argc, char* argv[])
{
    int oc;
    int aflg ,cflg ;
    aflg=cflg=0;
    char* b_opt_arg = NULL;
    while ( (oc = getopt(argc, argv, ":ab:c")) !=-1) {

        switch (oc) {
            case 'a' :
                aflg++;
                break;

            case 'b' :

                b_opt_arg = optarg;
                break;

            case 'c' :
                cflg++;
                break;

            case '?' ://无效选项                 break;

            case ':' ://选项缺少参数                 break;

            default:
                break;
            }
       }
   if (aflg)
      printf("This is -a option\n");
   if (b_opt_arg)
      printf("This is -b option\nits argument is %s\n", b_opt_arg);
   if (cflg)
      printf("This is -c option\n");

   return 0;
}
                 -----------------END CODE---------------------------

Linux Programming by Exemple(第二章 参数、选项..

Linux Programming by Exemple(第二章参数、选项..