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Re^2: Regex shows only last match multiple times?

by Anonymous Monk
on Aug 08, 2014 at 13:41 UTC ( #1096759=note: print w/replies, xml ) Need Help??


in reply to Re: Regex shows only last match multiple times?
in thread Regex shows only last match multiple times?

how to exit the loop after complete 3 rounds...?? it means... if you enter 3 times wrong input it should exit from the program... here i am providing code please modify it
#!/user/bin/perl print"enter the rang of array:\n"; chomp($c=<STDIN>); while($i=1){ print"while loop round:$i\n"; if($i>3){ exit; } if($c =~ /^\[|[a-z,A-Z]+/){ print "it is invalid please enter digits\n"; #print"enter the rang of array:\n"; #chomp($c=<STDIN>); } elsif($c =~ /^[1-9]+/){ print "you are entered correct input\n"; last; } $i++; } @a=(); $b; $1; print"Enter the array:\n"; for($i=0;$i<$c;$i++){ chomp($b=<STDIN>); $a[$i]=$b; } #for($i=0;$i<@a;$i++){ #print"the array $a[$i]\n"; #} #print"the PSI ID's:"; foreach $val(@a){ #print"####$val###\n"; if($val=~ /^([a-z]+)\s?PSI\-ID\-?(\d+)/){ print"value=$2\n"; push(@b,$1); push(@c,$2); } } print"the pax id's with PSI:\n"; for($i=0;$i<=@b;$i++){ for($j=0;$j<=@c;$j++){ if($i==$j){ print"$b[$i] $c[$j]\n"; } } }

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Re^3: Regex shows only last match multiple times?
by Athanasius (Archbishop) on Aug 08, 2014 at 15:51 UTC

    If you add use warnings; to the head of your script, Perl will tell you that the opening of the while loop:

    while ($i = 1) {

    contains a logic error: it re-initialises the variable to 1 on each loop iteration. In fact, this loop would benefit from a complete re-write:

    use strict; use warnings; my $c; for (my ($valid, $try) = (0, 1); !$valid; ++$try) { print "Enter the range of the array (try $try):\n"; chomp($c = <STDIN>); if ($c =~ /^\d+$/) { print "You have entered a valid range: $c\n"; $valid = 1; } elsif ($try < 3) { print "The input is invalid, please enter digits only\n"; } else { print "No valid array range entered, exiting\n"; exit; } } print "Continuing...\n";

    This is one of the unusual cases in which a C-style for loop is useful in Perl. Please note:

    • I have also added use strict; and declared all variables as lexicals with my. The amount of time this will save you down the track far outweighs the (very small) extra effort required.
    • In future, please put <code> ... </code> tags around your code, to make it readable.
    • When asking a question (as opposed to commenting on someone else’s answer), it’s usually better to open a new thread.

    Hope that helps,

    Athanasius <°(((><contra mundum Iustus alius egestas vitae, eros Piratica,

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