__concat(3) [netbsd man page]

__CONCAT(3)						   BSD Library Functions Manual 					       __CONCAT(3)

NAME

     __CONCAT, __STRING -- argument substitution

SYNOPSIS

     #include <sys/cdefs.h>

     xy
     __CONCAT(x, y);

     const char *
     __STRING(x);

DESCRIPTION

     The __CONCAT macro makes use of the cpp(1) preprocessor to concatenate two tokens.  When the macro is expanded, x and y are combined into a
     single token, provided that the result forms a valid token; two tokens that together do not form a valid token can not be concatenated.  This
     is known as ``token concatenation'' or ``token pasting''.

     The __STRING() macro uses the conventional '#' preprocessing operator to replace the argument x with a string literal.  This is also known as
     ``stringification''.

EXAMPLES

     The following two printf(3) calls produce the same output:

	   #define Net	   0x01
	   #define BSD	   0x02

	   #define NetBSD  "NetBSD"

	   (void)printf("%s
", __CONCAT(Net, BSD));
	   (void)printf("%s%s
", __STRING(Net), __STRING(BSD));

SEE ALSO

     cpp(1), cdefs(3)

HISTORY

     The __CONCAT() and __STRING() macros first appeared in NetBSD 1.3.

CAVEATS

     Many small details direct the proper use of the macros.  For example, while all leading and trailing whitespace is ignored when __STRING() is
     used, it is undefined whether cpp(1) puts white space between the tokens when __CONCAT() is used.	It can be also noted that the C preproces-
     sor converts all comments to whitespace before any macros are even considered.  The use of either macro is discouraged in complex constructs.

BSD
								 December 16, 2010							       BSD

GETSUBOPT(3)						   BSD Library Functions Manual 					      GETSUBOPT(3)

NAME

     getsubopt -- get sub options from an argument

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <stdlib.h>

     extern char *suboptarg;

     int
     getsubopt(char **optionp, char * const *tokens, char **valuep);

DESCRIPTION

     The getsubopt() function parses a string containing tokens delimited by one or more tab, space or comma (',') characters.	It is intended for
     use in parsing groups of option arguments provided as part of a utility command line.

     The argument optionp is a pointer to a pointer to the string.  The argument tokens is a pointer to a NULL-terminated array of pointers to
     strings.

     The getsubopt() function returns the zero-based offset of the pointer in the tokens array referencing a string which matches the first token
     in the string, or, -1 if the string contains no tokens or tokens does not contain a matching string.

     If the token is of the form ``name=value'', the location referenced by valuep will be set to point to the start of the ``value'' portion of
     the token.

     On return from getsubopt(), optionp will be set to point to the start of the next token in the string, or the null at the end of the string
     if no more tokens are present.  The external variable suboptarg will be set to point to the start of the current token, or NULL if no tokens
     were present.  The argument valuep will be set to point to the ``value'' portion of the token, or NULL if no ``value'' portion was present.

EXAMPLES

     char *tokens[] = {
	     #define ONE     0
		     "one",
	     #define TWO     1
		     "two",
	     NULL
     };

     ...

     extern char *optarg, *suboptarg;
     char *options, *value;

     while ((ch = getopt(argc, argv, "ab:")) != -1) {
	     switch(ch) {
	     case 'a':
		     /* process ``a'' option */
		     break;
	     case 'b':
		     options = optarg;
		     while (*options) {
			     switch(getsubopt(&options, tokens, &value)) {
			     case ONE:
				     /* process ``one'' sub option */
				     break;
			     case TWO:
				     /* process ``two'' sub option */
				     if (!value)
					     error("no value for two");
				     i = atoi(value);
				     break;
			     case -1:
				     if (suboptarg)
					     error("illegal sub option %s",
					       suboptarg);
				     else
					     error("missing sub option");
				     break;
			     }
		     }
		     break;
	     }
     }

SEE ALSO

     getopt(3), strsep(3)

HISTORY

     The getsubopt() function first appeared in 4.4BSD.

BSD
								 December 25, 2011							       BSD