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erl_format(3)		      C	Library	Functions		 erl_format(3)

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 Er-
	      lang	 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	 vari-
	      ables.

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

	      Term and Pattern are compared, and any unbound variables in Pat-
	      tern 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 3.7.20		 erl_format(3)

NAME | DESCRIPTION | EXPORTS

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