Count uppercase letters in string using perl

Question

I want to count the number of upper case letters in a string using perl.

For example: I need to know how many upper case characters the word "EeAEzzKUwUHZws" contains.

score 15 · Accepted Answer · answered Jul 11 '11 at 15:52

15

Beware of Unicode, as the straight A-Z thing isn't really portable for other characters, such as accented uppercase letters. if you need to handle these too, try:

my $result = 0;
$result++ while($string =~ m/\p{Uppercase}/g);

answered Jul 11 '11 at 15:52

Stuart Watt

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or just `$result = () = $string =~ m/\p{Uppercase}/g` – ysth Jul 11 '11 at 18:19
2

Do remember that `Uppercase` (alias `upper`) comprises more than merely `Uppercase_Letter` (alias `Lu`), although the former is more often appropirate than the latter is. Both, of course, ignore titlecase when those are distinct from uppercase. – tchrist Jul 12 '11 at 23:20

score 9 · Answer 2 · edited May 23 '17 at 12:24

9

Use the tr operator:

$upper_case_letters = $string =~ tr/A-Z//;

This is a common question and the tr operator usually outperforms other techniques.

edited May 23 '17 at 12:24

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answered Jul 11 '11 at 15:46

mob

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Well sure, but if you don’t care whether it gets the right answer or not, I can make any bit of code infinitely fast. ;( – tchrist Jul 12 '11 at 23:18

score 2 · Answer 3 · answered Jul 11 '11 at 15:49

2

sub count {
  $t = shift;
  $x = 0;   
  for( split//,$t ) {
    $x++ if m/[A-Z]/;
  }
  return $x;
}

answered Jul 11 '11 at 15:49

zellio

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score 0 · Answer 4 · edited May 23 '17 at 11:53

0

The one-liner method is:

$count = () = $string =~ m/\p{Uppercase}/g

This is based off Stuart Watt's answer but modified according to the tip that ysth posted in the comments to make it a one-liner.

edited May 23 '17 at 11:53

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answered Jan 07 '14 at 22:34

Ben Lee

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Count uppercase letters in string using perl

4 Answers4