Error-free constant folding is a TODO

[p5sagit/p5-mst-13.2.git] / pod / perltrap.pod

diff --git a/pod/perltrap.pod b/pod/perltrap.pod
index 6a6a443..0ad0086 100644 (file)
--- 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;
@@ -174,7 +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 *
 
@@ -206,6 +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 *
@@ -255,6 +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