Strings in Perl 6

Basic information about strings

1 How are strings stored in P6?

Strings are stored in a Scalar and are enclosed in single or double quotes.

my $name = 'John Doe';
my $name2 = "James Doe";

say $name;
say $name2;

Output:

$
John Doe
James Doe

2 What are some functions available for strings?

• chars - will return the number of characters in string.
• flip - will return the same string in reverse.
• Case handling
  • uc, lc - will uppercase, lowercase all characters in a string.
  • fc - "fold case" converts all chars to a form suitable for case-less comparisons. This page discusses case folding's challenges.
  • tc - "title case" upper-cases the 1st character in a string, leaving the rest.
  • tclc - Uppercase first char, lowercase the rest
  • wordcase - Uppercase each word. Can add rules, see S32 "Str" notes.

my $name = 'John Doe';

say $name.uc;
say $name.chars;
say $name.flip;

say 'Pass-Straße'.fc;

my $mixed_case='abC dEf ghI';
say 'tc=', $mixed_case.tc;
say 'tclc=', $mixed_case.tclc;
say 'wordcase=', $mixed_case.wordcase;

Output:

$
JOHN DOE
8
eoD nhoJ
pass-strasse
tc=AbC dEf ghI
tclc=Abc def ghi
wordcase=Abc Def Ghi

my $rv;
say 'chop():';
my $str1 = 'Pass-Straße';
say '$str1:              ', $str1;
my $str2 = $str1;
$rv = chop($str2, 3);
say 'after chop 3 chars: ', $rv;
say '';
say 'chomp():';
my $line1 = "foobar\n";
say '$line1:        ', "<$line1>";
$rv = chomp($line1);
say 'after chomp(): ', $rv;
my $line2 = "DOS\r\n";
say '$line2:        ', "<$line2>";
$rv = chomp($line2);
say 'after chomp(): ', $rv;
say '';
say 'From http://doc.perl6.org/type/Str#method_unival:';
say "'unival' returns numeric value of first codepoint, or NaN if not numeric";
say "'75'.unival: ", '75'.unival;
say "'¾'.unival:  ", '¾'.unival;
say "'A'.unival:  ", 'A'.unival;
say "";
say "'univals' returns list of numeric values of codepoints; NaN if not numeric";
say "'75¾A'.univals: ", '75¾A'.univals;
say "";
say "perl6 has no 'length' function; normally we would use 'chars' instead";
say "usually, a grapheme is a character";

(http://doc.perl6.org/type/Str#method_length)

say 'DOS' ~ '     ', chars('DOS');
say 'DOS\n' ~ '   ', chars("DOS\n");
say 'DOS\r\n' ~ ' ', chars("DOS\r\n");
say '¾' ~ '       ', chars('¾');
say "";
say 'encode function returns Blob:';
say q|$str1:                     |, $str1;
say q|$str1.encode('UTF-8')      |, $str1.encode('UTF-8');
say q|$str1.encode('UTF-16')     |, $str1.encode('UTF-16');
say q|$str1.encode('ISO-8859-1') |, $str1.encode('ISO-8859-1');

Output:

chop():
$str1:              Pass-Straße
after chop 3 chars: Pass-Str

chomp():
$line1:        <foobar
>
after chomp(): foobar
$line2:        <DOS
>
after chomp(): DOS

(http://doc.perl6.org/type/Str#method_unival)
'unival' returns numeric value of first codepoint, or NaN if not numeric
'75'.unival: 7
'¾'.unival:  0.75
'A'.unival:  NaN

'univals' returns list of numeric values of codepoints; NaN if not numeric
'75¾A'.univals: (7 5 0.75 NaN)

perl6 has no 'length' function; normally we would use 'chars' instead
usually, a grapheme is a character
(http://doc.perl6.org/type/Str#method_length)
DOS     3
DOS\n   4
DOS\r\n 4
¾       1

encode function returns Blob:
$str1:                     Pass-Straße
$str1.encode('UTF-8')      utf8:0x<50 61 73 73 2d 53 74 72 61 c3 9f 65>
$str1.encode('UTF-16')     utf16:0x<50 61 73 73 2d 53 74 72 61 df 65>
$str1.encode('ISO-8859-1') Blob[uint8]:0x<50 61 73 73 2d 53 74 72 61 df 65>

say 'index and rindex';
my $str = 'passacaglia and fugue';
say '      012345678901234567890';
say '$str: ', $str;
say q|index $str, 'p':                              |, index $str, 'p';
say q|index $str, 'u':                              |, index $str, 'u';
say q|index $str, 'u', 5:                           |, index $str, 'u', 5;
say q|index $str, 'u', 18:                          |, index $str, 'u', 18;
say q|index $str, 'x':                              |, index $str, 'x';
say q|index($str, 'x').defined ?? 'OK' !! 'NOT OK': |, index($str, 'x').defined ?? 'OK' !! 'NOT OK';
say q|rindex $str, 'p':                             |, rindex $str, 'p';
say q|rindex $str, 'u':                             |, rindex $str, 'u';
say q|rindex $str, 'u', 5:                          |, rindex $str, 'u', 5;
say q|rindex $str, 'x':                             |, rindex $str, 'x';

Output:

index and rindex
      012345678901234567890
$str: passacaglia and fugue
index $str, 'p':                              0
index $str, 'u':                              17
index $str, 'u', 5:                           17
index $str, 'u', 18:                          19
index $str, 'x':                              Nil
index($str, 'x').defined ?? 'OK' !! 'NOT OK': NOT OK
rindex $str, 'p':                             0
rindex $str, 'u':                             19
rindex $str, 'u', 5:                          Nil
rindex $str, 'x':                             Nil