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redo

Perl 5 version 8.8 documentation
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redo

Perl functions A-Z | Perl functions by category | The 'perlfunc' manpage
  • redo LABEL

  • redo

    The redo command restarts the loop block without evaluating the conditional again. The continue block, if any, is not executed. If the LABEL is omitted, the command refers to the innermost enclosing loop. Programs that want to lie to themselves about what was just input normally use this command:

    1.     # a simpleminded Pascal comment stripper
    2.     # (warning: assumes no { or } in strings)
    3.     LINE: while (<STDIN>) {
    4. 	while (s|({.*}.*){.*}|$1 |) {}
    5. 	s|{.*}| |;
    6. 	if (s|{.*| |) {
    7. 	    $front = $_;
    8. 	    while (<STDIN>) {
    9. 		if (/}/) {	# end of comment?
    10. 		    s|^|$front\{|;
    11. 		    redo LINE;
    12. 		}
    13. 	    }
    14. 	}
    15. 	print;
    16.     }

    redo cannot be used to retry a block which returns a value such as eval {} , sub {} or do {} , and should not be used to exit a grep() or map() operation.

    Note that a block by itself is semantically identical to a loop that executes once. Thus redo inside such a block will effectively turn it into a looping construct.

    See also continue for an illustration of how last, next, and redo work.