diff options
| -rw-r--r-- | pod/perldiag.pod | 3 | ||||
| -rw-r--r-- | pod/perlfaq8.pod | 2 | ||||
| -rw-r--r-- | pod/perlfunc.pod | 23 | ||||
| -rw-r--r-- | pod/perlop.pod | 2 | ||||
| -rw-r--r-- | pod/perlport.pod | 20 | ||||
| -rw-r--r-- | pod/perlutil.pod | 2 |
6 files changed, 29 insertions, 23 deletions
diff --git a/pod/perldiag.pod b/pod/perldiag.pod index a62d8d18e5..c142367e98 100644 --- a/pod/perldiag.pod +++ b/pod/perldiag.pod @@ -3567,8 +3567,7 @@ bad switch on your behalf.) (W newline) A file operation was attempted on a filename, and that operation failed, PROBABLY because the filename contained a newline, -PROBABLY because you forgot to chop() or chomp() it off. See -L<perlfunc/chomp>. +PROBABLY because you forgot to chomp() it off. See L<perlfunc/chomp>. =item Unsupported directory function "%s" called diff --git a/pod/perlfaq8.pod b/pod/perlfaq8.pod index d806ed67e7..1df3b6ac0a 100644 --- a/pod/perlfaq8.pod +++ b/pod/perlfaq8.pod @@ -321,7 +321,7 @@ go bump in the night, finally came up with this: # been opened on a pipe... system("/bin/stty $stty"); $_ = <MODEM_IN>; - chop; + chomp; if ( !m/^Connected/ ) { print STDERR "$0: cu printed `$_' instead of `Connected'\n"; } diff --git a/pod/perlfunc.pod b/pod/perlfunc.pod index ca14939c6d..c75818e04d 100644 --- a/pod/perlfunc.pod +++ b/pod/perlfunc.pod @@ -301,7 +301,7 @@ X<-S>X<-b>X<-c>X<-t>X<-u>X<-g>X<-k>X<-T>X<-B>X<-M>X<-A>X<-C> Example: while (<>) { - chop; + chomp; next unless -f $_; # ignore specials #... } @@ -630,23 +630,11 @@ characters removed is returned. =item chop Chops off the last character of a string and returns the character -chopped. It's used primarily to remove the newline from the end of an -input record, but is much more efficient than C<s/\n//> because it neither +chopped. It is much more efficient than C<s/.$//s> because it neither scans nor copies the string. If VARIABLE is omitted, chops C<$_>. -Example: - - while (<>) { - chop; # avoid \n on last field - @array = split(/:/); - #... - } - If VARIABLE is a hash, it chops the hash's values, but not its keys. -You can actually chop anything that's an lvalue, including an assignment: - - chop($cwd = `pwd`); - chop($answer = <STDIN>); +You can actually chop anything that's an lvalue, including an assignment. If you chop a list, each element is chopped. Only the value of the last C<chop> is returned. @@ -4443,13 +4431,12 @@ Example: open(PASSWD, '/etc/passwd'); while (<PASSWD>) { - ($login, $passwd, $uid, $gid, + chomp; + ($login, $passwd, $uid, $gid, $gcos, $home, $shell) = split(/:/); #... } -(Note that $shell above will still have a newline on it. See L</chop>, -L</chomp>, and L</join>.) =item sprintf FORMAT, LIST diff --git a/pod/perlop.pod b/pod/perlop.pod index ebe52c568e..464ba9917b 100644 --- a/pod/perlop.pod +++ b/pod/perlop.pod @@ -1746,7 +1746,7 @@ is roughly equivalent to: open(FOO, "echo *.c | tr -s ' \t\r\f' '\\012\\012\\012\\012'|"); while (<FOO>) { - chop; + chomp; chmod 0644, $_; } diff --git a/pod/perlport.pod b/pod/perlport.pod index 1078e58bf3..08a1704baf 100644 --- a/pod/perlport.pod +++ b/pod/perlport.pod @@ -94,6 +94,26 @@ from) C<\015\012>, depending on whether you're reading or writing. Unix does the same thing on ttys in canonical mode. C<\015\012> is commonly referred to as CRLF. +A common cause of unportable programs is the misuse of chop() to trim +newlines: + + # XXX UNPORTABLE! + while(<FILE>) { + chop; + @array = split(/:/); + #... + } + +You can get away with this on Unix and MacOS (they have a single +character end-of-line), but the same program will break under DOSish +perls because you're only chop()ing half the end-of-line. Instead, +chomp() should be used to trim newlines. The Dunce::Files module can +help audit your code for misuses of chop(). + +When dealing with binary files (or text files in binary mode) be sure +to explicitly set $/ to the appropriate value for your file format +before using chomp(). + Because of the "text" mode translation, DOSish perls have limitations in using C<seek> and C<tell> on a file accessed in "text" mode. Stick to C<seek>-ing to locations you got from C<tell> (and no diff --git a/pod/perlutil.pod b/pod/perlutil.pod index 7b56a17503..be7a345f79 100644 --- a/pod/perlutil.pod +++ b/pod/perlutil.pod @@ -97,7 +97,7 @@ Similarly, F<s2p> converts F<sed> scripts to Perl programs. F<s2p> run on C<s/foo/bar> will produce a Perl program based around this: while (<>) { - chop; + chomp; s/foo/bar/g; print if $printit; } |