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--- notes:perl_cheat_sheet [2026/07/17 19:58]
114.119.152.46 old revision restored (2026/06/25 08:12)
+++ notes:perl_cheat_sheet [2026/07/24 13:03] (current)
47.79.201.51 old revision restored (2026/06/15 21:28)
@@ Line 14: / Line 14: @@
   * Parenthesis are optional unless part of syntax.
   * ''@ARGV'' contains arguments, $0 contains program name.
+  * ''die''/''warn'' can be used to exit/warn, $! will contain any system error message. Without \n at the end, perl will append line number to error message.
 ===== Numbers =====
@@ Line 90: / Line 91: @@
   * ''<>'' iterates over all files in @ARGV (or STDIN if no args) like e.g. cat/sed/awk. <code perl>while (<>) {
     chomp;
-    print "It was $_ that I saw!\n";
+    print LOGFILE "It was $_ that I saw!\n";
 }</code>
+  * ''print'' takes list of items and sends all to STDOUT (unseparated). ''print @array;'' vs ''print "@array";'' <code perl>print <>;          # source code for 'cat'
+print sort <>;     # source code for 'sort'</code>
+  * C-like printf function %g for number auto-format,%10s, %-10d etc.<code perl>my @items = qw( wilma dino pebbles );
+my $format = "The items are:\n" . ("%10s\n" x @items);
+printf $format, @items;
+printf "The items are:\n".("%10s\n" x @items), @items;
+</code>
+  * Filehandles can be barewords (upper-cased) or variables. Special filehandles are : STDIN, STDOUT, STDERR, DATA, ARGV, and ARGVOUT .<code perl>open CONFIG, '<dino';  # < is optional
+open BEDROCK, '>fred' || die "Cannot open fred: $!";
+open LOG, '>>:encoding(UTF-8)','logfile'; # for perl >= 5.6
+open my $bedrock, '>:crlf', $file_name; # DOS-formatted output
+binmode STDOUT, ':encoding(UTF-8)';</code>
+  * ''select'' can be used to change default output filehandle. ''$| = 1;'' unbuffers currently selected output.
 ===== User Subroutines =====

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