perl's grep function with '^' and '$'

jesuashok has asked for the wisdom of the Perl Monks concerning the following question:

Fantasy monks,

Apologies If this has been discussed already,

# Program : 1
#!/usr/bin/perl

use strict;

my $match = 'A';

my @array = qq[Anthony Mark Alex A];
if ( grep( /^$match/,@array ) ) {
   print "Matched\n";
}
[download]

Output :
Matched
[download]

# Program : 2
#!/usr/bin/perl

use strict;

my $match = 'A';

my @array = qq[Anthony Mark Alex A];
if ( grep( /$match$/,@array ) ) {
   print "Matched\n";
}
<code>
Output :
Matched
[download]

# Program : 3
#!/usr/bin/perl

use strict;

my $match = 'A';

my @array = qq[Anthony Mark Alex A];
if ( grep( /^$match$/,@array ) ) {
   print "Matched\n";
}
[download]

What is the problem with the 3rd program ? am I missing something there ?

Comment on perl's grep function with '^' and '$' Select or Download Code

Replies are listed 'Best First'.
Re: perl's grep function with '^' and '$' by shmem (Chancellor) on May 25, 2007 at 09:13 UTC
Try: `perl -le 'my @array = qq[Anthony Mark Alex A]; print for @array'` [download] See? What does the `qq[]` operator do? you want `qw[]`. You would have spotted that had you written e.g. `# Program : 2 #!/usr/bin/perl use strict; my $match = 'A'; my @array = qq[Anthony Mark Alex A]; if ( my @list = grep( /$match$/,@array ) ) { print "Matched: ".join(', ', map {"'$_'"} @list)."\n"; } __END__ Matched: 'Anthony Mark Alex A'` [download] learn to debug... ;-) --shmem _($_=" "x(1<<5)."?\n".q·/)Oo. G°\ / /\_¯/(q / ---------------------------- \__(m.====·.(_("always off the crowd"))."· ");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}	[reply] [d/l] [select]
Re: perl's grep function with '^' and '$' by clinton (Priest) on May 25, 2007 at 09:13 UTC
Indeed you are, you should be using `qw` not `qq`. See perlop `# Program : 3 #!/usr/bin/perl use strict; my $match = 'A'; my @array = qw[Anthony Mark Alex A]; if ( grep( /^$match$/,@array ) ) { print "Matched\n"; }` [download]	[reply] [d/l] [select]
Re: perl's grep function with '^' and '$' by moritz (Cardinal) on May 25, 2007 at 09:16 UTC
The problem is in the quoting. `qq[...]` quotes a string, so your array has just one element - that happens to start with an A. use `qw(Anthony Mark Alex A)` and all is fine. Perl 6 in German	[reply] [d/l] [select]

Back to Seekers of Perl Wisdom