Course of Raku / Advanced / More about built-in types / Strings

Splitting and joining

Strings can be broken into parts and put back together in several ways.

The words method splits a string into a list of its whitespace-separated words:

say 'Hello big World'.words; # (Hello big World)

The split method breaks a string at a separator that you choose:

say 'a,b,c'.split(','); # (a b c)

An important special case is splitting on the empty string '': it breaks a string into its individual characters, but it also slips an empty string in at the very start and the very end, so the result has two elements more than you might expect:

say 'abc'.split('').elems;        # 5 — the three letters, plus an empty string at each end
say 'abc'.split('', :skip-empty); # (a b c) — the :skip-empty adverb drops the empties

To split into characters, the comb method, called without arguments, does it directly — with no stray empties to clean up:

say 'Raku'.comb; # (R a k u)

To go the other way, the join method glues a list of values into a single string, placing a separator between them:

say <a b c>.join('-'); # a-b-c

Two more methods work on parts of a string. The substr method extracts a piece, given a starting position and, optionally, a length:

say 'Hello World'.substr(0, 5); # Hello
say 'Hello World'.substr(6);    # World

And trim removes whitespace from both ends of a string:

say '  hi  '.trim; # hi

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