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<H1>erl_format</H1>
</CENTER>
<H3>C LIBRARY</H3>
<DIV CLASS=REFBODY>
erl_format
</DIV>
<H3>C LIBRARY SUMMARY</H3>
<DIV CLASS=REFBODY>
Create and Match Erlang Terms
</DIV>
<H3>DESCRIPTION</H3>
<DIV CLASS=REFBODY>
<P>This module contains two routines - one general function for
creating Erlang terms and one for pattern matching Erlang terms.
</DIV>
<H3>EXPORTS</H3>
<P><A NAME="erl_format/2"><STRONG><CODE>ETERM *erl_format(FormatStr, ... )</CODE></STRONG></A><BR>
<DIV CLASS=REFBODY><P>Types:
<DIV CLASS=REFTYPES>
<P>
<STRONG><CODE>char *FormatStr;</CODE></STRONG><BR>
</DIV>
</DIV>
<DIV CLASS=REFBODY>
<P>This is a general function for creating Erlang terms using
a format specifier and a corresponding set of arguments, much
in the way <CODE>printf()</CODE> works.
<P><CODE>FormatStr</CODE> is a format specification string. The set
of valid format specifiers is as follows:
<P>
<UL>
<LI>
~i - Integer<BR>
</LI>
<LI>
~f - Floating point<BR>
</LI>
<LI>
~a - Atom<BR>
</LI>
<LI>
~s - String<BR>
</LI>
<LI>
~w - Arbitrary Erlang term<BR>
</LI>
</UL>
<P>For each format specifier that appears in <CODE>FormatStr</CODE>,
there must be a corresponding argument following
<CODE>FormatStr</CODE>. An Erlang term is built according to the
<CODE>FormatStr</CODE> with values and Erlang terms substituted from
the corresponding arguments and according to the individual
format specifiers. For example:
<PRE>
erl_format("[{name,~a},{age,~i},{data,~w}]",
"madonna",
21,
erl_format("[{adr,~s,~i}]","E-street",42));
</PRE>
<P>This will create an <CODE>(ETERM *)</CODE> structure corresponding
to the Erlang term:
<CODE>[{name,madonna},{age,21},{data,[{adr,"E-street",42}]}]</CODE>
<P>The function returns an Erlang term, or NULL if
<CODE>FormatStr</CODE> does not describe a valid Erlang term.
</DIV>
<P><A NAME="erl_match/2"><STRONG><CODE>int erl_match(Pattern, Term)</CODE></STRONG></A><BR>
<DIV CLASS=REFBODY><P>Types:
<DIV CLASS=REFTYPES>
<P>
<STRONG><CODE>ETERM *Pattern,*Term;</CODE></STRONG><BR>
</DIV>
</DIV>
<DIV CLASS=REFBODY>
<P>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.
<P><CODE>Pattern</CODE> is an Erlang term, possibly containing unbound
variables.
<P><CODE>Term</CODE> is an Erlang term that we wish to match against
<CODE>Pattern</CODE>.
<P><CODE>Term</CODE> and <CODE>Pattern</CODE> are compared, and any
unbound variables in <CODE>Pattern</CODE> are bound to corresponding
values in <CODE>Term</CODE>.
<P>If <CODE>Term</CODE> and <CODE>Pattern</CODE> can be matched, the
function returns a non-zero value and binds any unbound
variables in <CODE>Pattern</CODE>. If <CODE>Term</CODE> <CODE>Pattern</CODE> do
not match, the function returns 0. For example:
<PRE>
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 */
...
}
</PRE>
<P><CODE>erl_var_content()</CODE> can be used to retrieve the
content of any variables bound as a result of a call to
<CODE>erl_match()</CODE>.
</DIV>
<H3>AUTHORS</H3>
<DIV CLASS=REFBODY>
T.Trnkvist - support@erlang.ericsson.se<BR>
</DIV>
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<SMALL>erl_interface 3.5.5.2<BR>
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<A HREF="http://www.erlang.se">Ericsson AB</A><BR>
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