1Filter::cpp(3)        User Contributed Perl Documentation       Filter::cpp(3)
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NAME

6       Filter::cpp - cpp source filter
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SYNOPSIS

9           use Filter::cpp ;
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DESCRIPTION

12       This source filter pipes the current source file through the C pre-
13       processor (cpp) if it is available.
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15       As with all source filters its scope is limited to the current source
16       file only. Every file you want to be processed by the filter must have
17       a
18
19           use Filter::cpp ;
20
21       near the top.
22
23       Here is an example script which uses the filter:
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25           use Filter::cpp ;
26
27           #define FRED 1
28           $a = 2 + FRED ;
29           print "a = $a\n" ;
30           #ifdef FRED
31           print "Hello FRED\n" ;
32           #else
33           print "Where is FRED\n" ;
34           #endif
35
36       And here is what it will output:
37
38           a = 3
39           Hello FRED
40
41       This example below, provided by Michael G Schwern, shows a clever way
42       to get Perl to use a C pre-processor macro when the Filter::cpp module
43       is available, or to use a Perl sub when it is not.
44
45           # use Filter::cpp if we can.
46           BEGIN { eval 'use Filter::cpp' }
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48           sub PRINT {
49               my($string) = shift;
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51           #define PRINT($string) \
52               (print $string."\n")
53           }
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55           PRINT("Mu");
56
57       Look at Michael's Tie::VecArray module for a practical use.
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AUTHOR

60       Paul Marquess
61

DATE

63       11th December 1995.
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67perl v5.36.0                      2022-08-18                    Filter::cpp(3)
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