X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=pod%2Fperltrap.pod;h=0ad0086a599a4656411bb92932a706b1cb099045;hb=6168cf9995a8bfcfe4ab9350ebc7de70215ae9af;hp=835f879949cb42a1b6852ee15de474a37e1c3bbb;hpb=418272e4394459ff8d3580f3ac6ed7225c26fa9a;p=p5sagit%2Fp5-mst-13.2.git

diff --git a/pod/perltrap.pod b/pod/perltrap.pod
index 835f879..0ad0086 100644
--- a/pod/perltrap.pod
+++ b/pod/perltrap.pod
@@ -18,6 +18,11 @@ Accustomed B<awk> users should take special note of the following:
 
 =item *
 
+A Perl program executes only once, not once for each input line.  You can
+do an implicit loop with C<-n> or C<-p>.
+
+=item *
+
 The English module, loaded via
 
     use English;
@@ -143,9 +148,9 @@ gives you.
 
 =back
 
-=head2 C Traps
+=head2 C/C++ Traps
 
-Cerebral C programmers should take note of the following:
+Cerebral C and C++ programmers should take note of the following:
 
 =over 4
 
@@ -159,13 +164,14 @@ You must use C<elsif> rather than C<else if>.
 
 =item *
 
-The C<break> and C<continue> keywords from C become in
-Perl C<last> and C<next>, respectively.
-Unlike in C, these do I<not> work within a C<do { } while> construct.
+The C<break> and C<continue> keywords from C become in Perl C<last>
+and C<next>, respectively.  Unlike in C, these do I<not> work within a
+C<do { } while> construct.  See L<perlsyn/"Loop Control">.
 
 =item *
 
-There's no switch statement.  (But it's easy to build one on the fly.)
+There's no switch statement.  (But it's easy to build one on the fly,
+see L<perlsyn/"Basic BLOCKs and Switch Statements">)
 
 =item *
 
@@ -173,7 +179,9 @@ Variables begin with "$", "@" or "%" in Perl.
 
 =item *
 
-Comments begin with "#", not "/*".
+Comments begin with "#", not "/*" or "//".  Perl may interpret C/C++
+comments as division operators, unterminated regular expressions or
+the defined-or operator.
 
 =item *
 
@@ -205,6 +213,11 @@ Seasoned B<sed> programmers should take note of the following:
 
 =item *
 
+A Perl program executes only once, not once for each input line.  You can
+do an implicit loop with C<-n> or C<-p>.
+
+=item *
+
 Backreferences in substitutions use "$" rather than "\".
 
 =item *
@@ -254,6 +267,13 @@ The arguments are available via @ARGV, not $1, $2, etc.
 The environment is not automatically made available as separate scalar
 variables.
 
+=item *
+
+The shell's C<test> uses "=", "!=", "<" etc for string comparisons and "-eq",
+"-ne", "-lt" etc for numeric comparisons. This is the reverse of Perl, which
+uses C<eq>, C<ne>, C<lt> for string comparisons, and C<==>, C<!=> C<< < >> etc
+for numeric comparisons.
+
 =back
 
 =head2 Perl Traps
@@ -1223,6 +1243,10 @@ repeatedly, like C</x/> or C<m!x!>.
     # perl4 prints: perl4
     # perl5 prints: perl5
 
+=item * Regular Expression
+
+Unlike in Ruby, failed matches in Perl do not reset the match variables
+($1, $2, ..., C<$`>, ...).
 
 =back