Comparing lower to upper case

bobothesmart has asked for the wisdom of the Perl Monks concerning the following question:

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Re: Comparing lower to upper case by Kanji (Parson) on Jun 11, 2002 at 18:21 UTC
If you only need things to be the same case for the comparison, then you can use uc or lc to force your strings to be upper or lower. `if ( uc($str) eq uc($something) ) { # ... }` [download] Alternately, and if you need care about the original case, you can reassign `$str` to an upper- or lowercased version of itself before you do anything else. `$str = uc($str); # force uppercase` --k.	[reply] [d/l] [select]
Re: Re: Comparing lower to upper case by bobothesmart (Initiate) on Jun 11, 2002 at 18:57 UTC
My statement looks like this: $fields[[0]] = uc($fields[[0]]); However, it does change this: 7f8954 into 7F8954. Id there a way to explicitely change just the one letter to uppercase? SORRY! It should say that it does NOT convert 7f8954 to 7F8954	[reply]
Re: Re: Re: Comparing lower to upper case by joshua (Pilgrim) on Jun 11, 2002 at 19:50 UTC
However, it does change this: 7f8954 into 7F8954. What? I thought that's what you wanted it to do... SORRY! It should say that it does NOT convert 7f8954 to 7F8954 I'm confused now. You mean `$fields[0] = uc($fields[0]);` isn't converting 7f8954 to 7F8954? `$fields[0] = "7f8954"; $fields[0] = uc($fields[0]);` [download] `$fields[0]` should now have a value of "7F8954" `$fields[0] =~ tr/a-z/A-Z/;` will also work. Joshua	[reply] [d/l] [select]
Re: Comparing lower to upper case by vladb (Vicar) on Jun 11, 2002 at 18:28 UTC
Answering your first question: 1. Figure out if the second character is a letter of the alphabet? You could simply do a pattern match, like so: `if ($str =~ m/\d[a-zA-Z]\d+/) { print "Ok!\n"; } else { print "Invalid format! Must be: [digit][letter][digit][digit] ... \n +"; }` [download] UPDATE: pardon for this minor slip, but you are certainly right. It should have been `[a-zA-Z]` instead of just `\w`. ;/. _____________________ open(I,$0);<I>;$~=$/;$/='~';$_=<I>;($/)=/(.)$~/;s/[$~~]//g;/(v)/;$-=$-[0];s;\Q$/\E;$~;g;($/,$^)=/^(.)(.)/; #% xxxxxx xx-+ xx xxx xx xx xx xx xxx xxxxx+ xx xx xxxx xxxxx ......+ #x xxxxvxxx xx xx xv xxxx x+ %+ ===== xx xx xx xx x+ =x xx xx xx xx xx ...+ #x xx xx xx xx xx xx xx xx xxx+ xxxxxx xx +x xx xx+x- xxxx xxxx ........+ #% xx xx xx xx xx xx xx x+ xx xx =+=== xx xx xxxx-xx xx =x +x xx xx xx xx ...+ #% xx xx xx -+x+ xxx+ xx xx xx xx xx x+ xx xxx+xx xx xx xxxx xx xx ....+~ for(split/$~/){s,[ $/],,g;/(.)$/;$l=$-[0];/(.)/\|\|next;$_=chr$-+$l;$".=($1=~/$^/)?" \u$_":$_;}print$";	[reply] [d/l] [select]
Re: Re: Comparing lower to upper case by jsprat (Curate) on Jun 11, 2002 at 18:44 UTC
But... `\w` will match any "word character", which is defined as "alphanumeric plus '_'", so that regex will match '2_4' and '234' as well as '2A4'. You'd need either `/\d[a-zA-Z]\d+/` or `/\d[:alpha:]\d+/`.	[reply] [d/l] [select]
Re: Re: Comparing lower to upper case by joshua (Pilgrim) on Jun 11, 2002 at 19:01 UTC
Won't \w match any letter, number, or underscore? `if ($str =~ m/\d[A-Z]\d+/) { print "Ok!\n"; } else { print "Invalid format! Must be: [digit][letter][digit][digit] ... \n +"; }` [download] Joshua	[reply] [d/l]
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Re: Comparing lower to upper case by insensate (Hermit) on Jun 11, 2002 at 19:41 UTC
Why not `$str=~tr/a-z/A-Z/;` This will leave all the digits alone and just change the lowercase characters to uppercase. -Jason	[reply] [d/l]
Re: Comparing lower to upper case by Abigail-II (Bishop) on Jun 12, 2002 at 14:16 UTC
Figure out if the second character is a letter of the alphabet? `if (substr ($str, 1, 1) =~ /[[:alpha:]]/) { .. }` [download] Convert that character to its uppercase form? `substr ($_, 1, 1) = uc substr ($_, 1, 1);` [download] Abigail	[reply] [d/l] [select]