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

[Anonymous Monk]

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";
        }
    }
}

[Athanasius]

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,