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For 2023 (and 2024 ...) - we are now fully retired from IT training.
We have made many, many friends over 25 years of teaching about Python, Tcl, Perl, PHP, Lua, Java, C and C++ - and MySQL, Linux and Solaris/SunOS too. Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own risk.

Lisa and I (Graham) now live in what was our training centre in Melksham - happy to meet with former delegates here - but do check ahead before coming round. We are far from inactive - rather, enjoying the times that we are retired but still healthy enough in mind and body to be active!

I am also active in many other area and still look after a lot of web sites - you can find an index ((here))
Perl - redo and last without a loop

Perl has next, last and redo commands which (by default) cause you to move on to the next iteration / exit from / repeat the same iteration of a loop.

Did you know that you can also label a block and then use them in a similar way in that block?


$c = 1;
$d = 4;
thyme:
{
$c++;
$e = 5;
redo thyme if ($c < 3);
$f = 6;
last thyme if ($e > 3);
$g = 7;
}
$h = 8;
print ("$c $d $e $f $g $h\n");


Result:


[localhost:~/dplp] graham% perl blocker
3 4 5 6 8
[localhost:~/dplp] graham%


Note - the "redo" lets you write a loop without there being any loop word used - dangerous unless you know what you're doing and almost as frowned upon as using a goto statement (of which Perl has three flavours!). See intermediate and advanced examples.
(written 2004-12-02, updated 2006-06-05)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
P206 - Perl - More Loops and Conditionals
  [299] What - no switch or case statement? - (2005-05-03)
  [657] The ternary operator in Python - (2006-03-25)
  [962] Breaking a loop - Ruby and other languages - (2006-12-03)
  [1191] Smart English Output - via PHP and Perl ? : operator - (2007-05-18)
  [1220] for loop - how it works (Perl, PHP, Java, C, etc) - (2007-06-06)
  [1582] Ruby, C, Java and more - getting out of loops - (2008-03-19)
  [1696] Saying NOT in Perl, PHP, Python, Lua ... - (2008-07-04)
  [1825] Question Mark - Colon operator (Perl and PHP) - (2008-10-08)
  [2711] For loop - checked once, or evety time? Ruby v Perl comparison and contrast - (2010-04-07)
  [2815] switch and case, or given and when in Perl - (2010-06-17)
  [2817] Setting a safety net or fallback value in Perl - (2010-06-19)
  [2824] A pint of Black Rat, and a lazy barman - (2010-06-25)
  [2832] Are you learning Perl? Some more examples for you! - (2010-06-27)
  [2892] Alternative loops and conditionals in Ruby and Perl - (2010-07-28)
  [2967] Multiway branches in Perl - the given and when syntax - (2010-09-22)
  [2972] Some more advanced Perl examples from a recent course - (2010-09-27)
  [3200] How a for loop works Java, Perl and other languages - (2011-03-12)
  [3398] Perl - making best use of the flexibility, but also using good coding standards - (2011-08-19)
  [3619] Ruby v Perl - a comparison example - (2012-02-21)
  [3914] While, for, foreach or something else to loop. - (2012-11-06)


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