Shell Programming and Scripting

print $hash{$value} if exists $hash{$key};

would only print my top value, and not the one I want to "match".... should i not be using if exists? how would you recommend "searching" a hash file...

thanks!

I assume you want to do something like this:

print $hash{$key} if exists $hash{$key};

If not, you need to elaborate more on what you are doing.

My hash, for example, looks like this

One 1
Two 2
Three 3


The user is prompted to enter in a word:

my $input = <STDIN>;
chomp $input;

I first wanted to use this if equals, but not sure if I can implement, so I tried something like this:

my $blah;
for $blah (keys(%hash)) {
if ($input eq $hash{$blah}) {
print "$hash{$blah}";
}
else {
print "no";
}
}

Playing around with this, entering Three, I might get:
nono3

or if I use a last;
no

I guess just looking for an easy way to look through a hash for a key, and print the value. If you could point me in the right direction, it would be very helpful.

Update, I made it through this by using:


if (exists $hash{$input}) {
print "This is equal to $hash{$input}\n";
}
else {
print "Not in hash\n";
}

So, if the user enters One, what prints is:
This is equal to 1

Now, I'm trying to go backwards, entering the value, and trying to get the key, so if the user enters 1, what prints is:
This is equal to One

Not sure how to go about this.... Learning, though!

See if key is in a hash:

Code:

my $input = 'one';
chomp $input;
print exists $hash{$input} ? $hash{$input} : "$input is not a hash key";

Find a hash key given a value:

Code:

my $input = '1';
chomp $input;
foreach my $key (keys %hash) {
   if ($hash{$key} eq $input) {
      print "The key for $input is $key\n";
   }
}

Thanks, unfortunately what's happening when I implement that script with an else statement that prints "no key found for value" is, if the value is the third in the hash, for example:

no key found for valueno key found for valueThe key for 1 is One

Any ideas? I want an "error message" for if the user enters something that's not a value....

One way:

Code:

my $input = '1';
chomp $input;
my $flag = 0;
foreach my $key (keys %hash) {
   if ($hash{$key} eq $input) {
      print "The key for $input is $key\n";
      $flag++;
   }
}
unless ($flag) {
   print "There is no key for $input\n";
}