[SOLVED] Perl: Test if string is uppercase

kenneho · 01-06-2010, 04:37 AM

Hi.

In my perl script I'd like to test if a string is written in uppercase letters or not. How can I do that? This type of test don't seem to work, so there must be other ways of doing this:

Code:

if ("hello" == "HELLO") { .... }

...return true.

I can create a subroutine that compares each character aginst a list of uppercase letters, but I'm hoping there's allready a build in routine in perl that does this...

Any ideas?

- kenneho

ashok.g · 01-06-2010, 04:43 AM

I am new to perl but I think we can get that using the following little snippet.

Code:

$a="HELLO";
if ( $a eq "\U$a" )
{
print $a;
}

kenneho · 01-06-2010, 05:35 AM

Thansk for your tip, but I didn't quite get it to work. This code:

Code:

#/usr/bin/perl 
$my_string = "hello"; 
if ($my_string =~ /[A-Z]*/) { 
    print "$my_string is uppercase.\n"; 
}

resultet in this output:

Code:

hello is uppercase.

Is it maybe necessary to loop through alle the characters, performing that same test?

kenneho · 01-06-2010, 05:53 AM

I caved in, and made use of this function I found somewhere on the net:

Code:

sub is_uppercase { 
    my ($string) = @_; 
    @splitit = split //, $string; 
    for (@splitit) { 
        # Checking each character if its uppercase...
        if ($_ !~ /(A|B|C|D|E|F|G|H|I|J|K|L|M|N|O|P|Q|R|S|T|U|V|W|X|Y|Z)/) { 
            # We found a lowercase character! 
            return undef; 
        } 
    } 
    return 1; 
}

I find it strange if perl doesn't have built in functions for checking if a string is uppercase or not. :/

syg00 · 01-06-2010, 06:17 AM

I'd guess you are using a UTF locale - and hence collating sequence. Try it as

Code:

if ($my_string =~ "\U$my_string") {

ashok.g · 01-06-2010, 06:26 AM

Quote:

Originally Posted by kenneho

I find it strange if perl doesn't have built in functions for checking if a string is uppercase or not. :/

It's not true . We have the functions in perl which can convert your string to lowercase as well as the upper case.

For Converting to LOWER case we have "lc". USAGE: lc "HELLO"
For Converting to UPPER case we have "uc". USAGE: uc "hello"

ashok.g · 01-06-2010, 06:38 AM

I made some changes to my code and its now edited. Hope that will help you.

kenneho · 01-06-2010, 07:38 AM

Quote:

Originally Posted by ashok.g

It's not true . We have the functions in perl which can convert your string to lowercase as well as the upper case.

For Converting to LOWER case we have "lc". USAGE: lc "HELLO"
For Converting to UPPER case we have "uc". USAGE: uc "hello"

Thanks for the tip, but I don't need to convert the string, I need to check if a string is uppercase...

kenneho · 01-06-2010, 07:39 AM

Quote:

Originally Posted by ashok.g

I made some changes to my code and its now edited. Hope that will help you.

Cool, I'll give it a try!

kenneho · 01-06-2010, 07:41 AM

Quote:

Originally Posted by kenneho

Cool, I'll give it a try!

I work! Great. "eq" instead of "==" was the solution. Thanks.

Telemachos · 01-06-2010, 03:31 PM

Quote:

Originally Posted by kenneho

Thanks for the tip, but I don't need to convert the string, I need to check if a string is uppercase...

Right, but think a bit more...

Code:

if ($string eq uc($string)) {
    # It's uppercase
}

That way, you don't need to know in advance what's stored in $string.

PMP · 01-07-2010, 01:50 AM

To add up to all your solution, The following code should work for the problem.

Code:

my $str = "STRING\n";
if ($str !~ /[a-z]/)
{
        print "$str The string is uppercase\n";
}
else
{
        print "$str contains lowercase characters\n";
}

syg00 · 01-07-2010, 03:55 AM

Doesn't pay to presume too much - does "upper/lower case" imply "ONLY upper/lower case" ?.
Stick a non alpha (say a digit) in the test string and run the tests above ...

ashok.g · 01-07-2010, 04:02 AM

Quote:

Originally Posted by syg00

Stick a non alpha (say a digit) in the test string and run the tests above ...

If that is the case then we have to go for checking each and every character with [A-Z]. Isn't it?

kenneho · 01-07-2010, 08:47 AM

Quote:

Originally Posted by Telemachos

Right, but think a bit more...

Code:

if ($string eq uc($string)) {
    # It's uppercase
}

That way, you don't need to know in advance what's stored in $string.

Yeah, this is a more neat way of doing it (which I happened to have allready done