Re: matching a regular expression

You can use index to good effect like this:

use strict;
use warnings;

my $state;
my $firstAttempt = 1;

while (1) {
    if($firstAttempt) {
        $state = promptUser("What network to listen for SNMP traps [hs
+bn or admin]? ", "admin"); ;
        $firstAttempt = 0;
    } else {
        $state = lc promptUser("ERROR: $state Invalid Re-enter the net
+work");
    }
    
    if (0 == index 'hsbn', $state) {
        $state = 'hsbn';
        last;
    } elsif (0 == index 'admin', $state) {
        $state = 'admin';
        last;
    }
}

if ($state eq 'hsbn') {
    #some action
}
[download]

Note that if you need to disambiguate between two strings that match for the first few characters you can require some number of characters thus:

    if (0 == index 'hsbn', $state and length ($state) >= 2) {
[download]

DWIM is Perl's answer to Gödel

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Re^2: matching a regular expression by blazar (Canon) on May 18, 2006 at 10:57 UTC
Note that if you need to disambiguate between two strings that match for the first few characters you can require some number of characters thus: Or else one may proceed like thus: `my @matching=grep { 0 == index $_, $userinput } @commands;` [download] Then take actions according to whether `@matching==0`, `@matching==1` or `@matching>=2`. In the latter case depending on what the commands are actually supposed to do I would either emit a warning and decide upon priority (which may be given by the ordering of `@commands` itself) or ask the users to refine their input. Update: minimal example follows. `#!/usr/bin/perl use strict; use warnings; my @commands=qw/foo bar baz/; print "Choose command [@commands]\n"; { chomp(my $cmd=<STDIN>); my @ok=grep { 0 == index $_, $cmd } @commands; print "You chose [@ok]\n" and last if @ok==1; warn +(@ok>1 ? "Ambiguos command [@ok]" : "Invalid command"), ", retry!\n"; redo; } __END__` [download] Usage example: `$ ./foo.pl Choose command [foo bar baz] fred Invalid command, retry! fo You chose [foo] $ ./foo.pl Choose command [foo bar baz] ba Ambiguos command [bar baz], retry! bar You chose [bar]` [download]	[reply] [d/l] [select]

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Re^2: matching a regular expression
by blazar (Canon) on May 18, 2006 at 10:57 UTC

Note that if you need to disambiguate between two strings that match for the first few characters you can require some number of characters thus:

Or else one may proceed like thus:

my @matching=grep { 0 == index $_, $userinput } @commands;
[download]

Then take actions according to whether @matching==0, @matching==1 or @matching>=2. In the latter case depending on what the commands are actually supposed to do I would either emit a warning and decide upon priority (which may be given by the ordering of @commands itself) or ask the users to refine their input.

Update: minimal example follows.

#!/usr/bin/perl

use strict;
use warnings;

my @commands=qw/foo bar baz/;
print "Choose command [@commands]\n";
{
    chomp(my $cmd=<STDIN>);
    my @ok=grep { 0 == index $_, $cmd } @commands;
    print "You chose [@ok]\n" and last if @ok==1;
    warn +(@ok>1 ?
        "Ambiguos command [@ok]" :
        "Invalid command"), ", retry!\n";
    redo;
}

__END__
[download]

Usage example:

$ ./foo.pl
Choose command [foo bar baz]
fred
Invalid command, retry!
fo
You chose [foo]
$ ./foo.pl
Choose command [foo bar baz]
ba
Ambiguos command [bar baz], retry!
bar
You chose [bar]
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[reply]
[d/l]
[select]