how to nullify case sensitivity

[iphone]

Hi, I have the below if condition,how do I make sure to nullify the caps lock difference in the condtion?

if ($b ne $a) {
}

[GrandFather]

Use lc or uc to normalise the strings you want to compare:

if (lc $var1 ne lc $var2) {
    ...
}

Note by the way that $a and $b are special variables used by sort and should generally not be used for other purposes - even in example code.

[Anonymous Monk]

use a function to lower case or upper case $a and $b (both special variables) before doing the comparison

perlfunc, perlintro, super search

[kcott]

Are you aware that $a and $b are special variables (see perlvar) used by sort. Unless you are using them in that context, you would be well advised to pick different variable names.

The condition you're after can be written as:

if (lc($var1) ne lc($var2)) { ... }

[CountZero]

There is more than one way to do it:

use Modern::Perl;

while (my $first = <DATA>) {
    my $second = <DATA>;
    chomp $first;
    chomp $second;
    say "Is >$first< equal to >$second<? ", ($first =~ m/^$\Qsecond\E$
+/i)?'Yes':'No';
}

__DATA__
test
TEST
testing
testing
TESTED
TESTED
TeStS
tEsTs
a Test
another Test

Output:

Is >test< equal to >TEST<? Yes
Is >testing< equal to >testing<? Yes
Is >TESTED< equal to >TESTED<? Yes
Is >TeStS< equal to >tEsTs<? Yes
Is >a Test< equal to >another Test<? No

Update: added the quotemeta tags \Q \E.</inq>

[Anonymous Monk]

You forgot quotemeta :)

m/^\Q$second\E$/i

[CountZero]

Indeed! Thank you for reminding me.

[ikegami]

If you wanted to use Unicode's definition of case insensitivity — they are the experts in this area — you should convert the strings to fold case (not lower case or upper case) and then compare them. The simplest way of doing that is:

$s1 =~ /^\Q$s2\E\z/i

Like the lc and uc methods, this assumes the string has previously been normalised. All together,

use Unicode::Normalize qw( NFC );

$s1 = NFC($s1);
$s2 = NFC($s2);
$s1 =~ /^\Q$s2\E\z/i