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Linux 2.6 - man page for erl_format (linux section 3erl)

erl_format(3erl)		       C Library Functions			 erl_format(3erl)

NAME
       erl_format - Create and Match Erlang Terms

DESCRIPTION
       This module contains two routines - one general function for creating Erlang terms and one
       for pattern matching Erlang terms.

EXPORTS
       ETERM * erl_format(FormatStr, ... )

	      Types  char *FormatStr;

	      This is a general function for creating Erlang terms using a format specifier and a
	      corresponding set of arguments, much in the way printf() works.

	      FormatStr  is  a format specification string. The set of valid format specifiers is
	      as follows:

		* ~i - Integer

		* ~f - Floating point

		* ~a - Atom

		* ~s - String

		* ~w - Arbitrary Erlang term

	      For each format specifier that appears in FormatStr , there must be a corresponding
	      argument	following  FormatStr . An Erlang term is built according to the FormatStr
	      with values and Erlang terms  substituted  from  the  corresponding  arguments  and
	      according to the individual format specifiers. For example:

	      erl_format("[{name,~a},{age,~i},{data,~w}]",
			 "madonna",
			 21,
			 erl_format("[{adr,~s,~i}]","E-street",42));

	      This  will  create  an  (ETERM  *)  structure  corresponding  to	the  Erlang term:
	      [{name,madonna},{age,21},{data,[{adr,"E-street",42}]}]

	      The function returns an Erlang term, or NULL if FormatStr does not describe a valid
	      Erlang term.

       int erl_match(Pattern, Term)

	      Types  ETERM *Pattern,*Term;

	      This  function  is used to perform pattern matching similar to that done in Erlang.
	      Refer to an Erlang manual for matching rules and more examples.

	      Pattern is an Erlang term, possibly containing unbound variables.

	      Term is an Erlang term that we wish to match against Pattern .

	      Term and Pattern are compared, and any unbound variables in Pattern  are	bound  to
	      corresponding values in Term .

	      If Term and Pattern can be matched, the function returns a non-zero value and binds
	      any unbound variables in Pattern . If Term  Pattern  do  not  match,  the  function
	      returns 0. For example:

	      ETERM *term, *pattern, *pattern2;
	      term1    = erl_format("{14,21}");
	      term2    = erl_format("{19,19}");
	      pattern1 = erl_format("{A,B}");
	      pattern2 = erl_format("{F,F}");
	      if (erl_match(pattern1, term1)) {
		/* match succeeds:
		 * A gets bound to 14,
		 * B gets bound to 21
		 */
		...
	      }
	      if (erl_match(pattern2, term1)) {
		/* match fails because F cannot be
		 * bound to two separate values, 14 and 21
		 */
		...
	      }
	      if (erl_match(pattern2, term2)) {
		/* match succeeds and F gets bound to 19 */
		...
	      }

	      erl_var_content()  can  be used to retrieve the content of any variables bound as a
	      result of a call to erl_match() .

Ericsson AB			       erl_interface 3.7.3			 erl_format(3erl)


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