boost_1_45_0/libs/test/test/test_files/test_ifdef.cfg

$define a aa
$ifdef a
1
$else
2
$endif

$ifdef A
1
$else
2
$endif

$ifndef A
1
$else
2
$endif

$ifdef a
$define V abc
$else
$define V cba
$endif

1$V$

$ifdef a
$ifdef V
a
$else
b
$endif
$else
c
$endif