Checking for empty string

[qazs]

Hi,
How can I check for empty string?
I tried using:
$string = "";
if($string eq ""){print "empy";}

but if $string = " " or " ";
this will not work.

Any help is appreciated.

[mlseim]

How about the reverse of "if" which is, "unless" ...

unless($string){
#do this if $string is null;
}


For the example you gave, you need to remember that strings and integers get compared differently. Integers: == (equal) Strings: eq (equal)

For Integers:
if($number == 12){
# do this if $number is 12.
}

For Strings:
if($string eq "codingforums"){
# do this
}

====================

EDIT:

And now I see that I misunderstood your original question.

A "space" is actually a character, so the $string is not empty (or null).

$string = " "; #this is a space.
$string = ""; #this is null.

You could filter out all of the spaces just for checking the $string.
$FILTER allows a-z, caps A-Z, numbers 0-9 ... everything else is removed.

$FILTER = "a-zA-Z0-9";
$test = $string;
$test =~ s/[^$FILTER]//go;

if($test){
#do this here, since $test is NOT null, there must be more
#characters than just a space.
}



.

[bazz]

have you tried

if (!string) {
the string variable is empty;
} else { there's something in the string
}

might work for you as it has for me.

Bazz

[qazs]

thanks i will try that.

[jmh0]

These answers are so lame I was forced to sign up for the site just to post this...

perl -ae '$a = "\t \n"; print "hello world!\n" if ($a =~ /^\s*$/);'

ie. if $a contains nothing (the asterisk,* takes care of this), or any other space characters (\s), from beginning (^) to end ($).

jmh0

[oesxyl]

These answers are so lame I was forced to sign up for the site just to post this...

perl -ae '$a = "\t \n"; print "hello world!\n" if ($a =~ /^\s*$/);'

ie. if $a contains nothing (the asterisk,* takes care of this), or any other space characters (\s), from beginning (^) to end ($).

jmh0
why did you use -a?

regards

[KevinADC]

These answers are so lame I was forced to sign up for the site just to post this...

perl -ae '$a = "\t \n"; print "hello world!\n" if ($a =~ /^\s*$/);'

ie. if $a contains nothing (the asterisk,* takes care of this), or any other space characters (\s), from beginning (^) to end ($).

jmh0


Yea, and they were lame three years ago when they were originally posted. ;)

[oesxyl]

Yea, and they were lame three years ago when they were originally posted. ;)
I miss that, :)

best regards

[FishMonger]

jmh0,

No one forced you to do anything, including signing up and responding to a 3yr old thread.

Your answer isn't as good as you think. Firstly, you used the -a switch for absolutely no reason and secondly, testing the length would be more efficient than the regex.

perl -e '$a = "\t \n"; print "hello world!\n" if length $a;'

[KevinADC]

jmh0,

No one forced you to do anything, .....

Maybe he was kidnapped at gun point and forced to sign up. :eek:

[MohitVohra]

I wanted to say thanks to bazz as I've tried bazz's suggestion and it worked wonders! I don't know about other versions of perl, I'm using ActivePerl 5.8 and it worked well on that, so I'm pretty satisfied with this answer.

Thanks a lot bazz for your answer and hope I didn't offend anyone by my comments.