There are two syntax forms for this function:

uc EXPR 
uc

to see a lot of fully commented examples that help you use the Perl statements and the Perl buit-in functions in your scripts.

# initialize some string variable
my $string = "This is about Perl Functions";
uc($string);
print $string, "\n";
# displays: This is about Perl Functions
$string = uc($string);
print $string, "\n";
# displays: THIS IS ABOUT PERL FUNCTIONS

This uc function is very useful when you perform some string comparisons. Try to remember that all comparisons are case sensitive and the following strings "uc" and "UC" are not the same.

Now let’s consider the case insensitive comparison of two strings. We can use the uc function either converting both strings in lowercases using an assignment operator and than make the comparisons or compare the strings by calling the uc function for each of them, without changing their values.

The next short example shows you how to do this:

my $string1 = "blue";
my $string2 = "Blue";
$string1 = uc($string1);
$string2 = uc($string2);
if($string1 eq $string2)	
{
  print "The two strings are equal\n";
}

#comparison without altering the string values

$string1 = "blue";
$string2 = "Blue";
if(uc($string1) eq uc($string2))
{
  print "The two strings are equal\n";
}