Try Text::CPP. It's light, fast, and easy to use.

#!/usr/bin/perl

use strict;
use warnings;
use Text::CPP; 

my $MyData = <DATA>;

my $reader = new Text::CPP( 
    Language => 'STDC99', 
    Options => {}, 
    Builtins => { 
        foo => 'this', 
        bar => 'that', 
    }, 
); 
$reader->read('/root/Desktop/file.c'); 
while (my $token = $reader->token) { 
    print "Token: $token\n"; 
} 
$reader->data->{MyKey} = $MyData;

__DATA__
#ifdef pathtest
38. This should appear.
#else
#define pathtest
37. This should appear.
#include test.txt
39. This should appear.
#undef pathtest
#endif
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