Course of Raku / Essentials / Strings

Escaping special characters

Imagine you want to print a price label, and you keep both the name of the product and its price in scalar variables?

my $product = 'Electricity';
my $price = 3.14;

How do you print the label if the price is meant to be in dollars? The expected output is: Electricity costs $3.14. A dollar sign in double-quoted strings is an indicator of a variable to be interpolated. To print the $ character itself, you need to escape it:

say "$product costs \$$price";

Of course, you can use string concatenation and avoid escaping $:

say $product ~ ' costs $' ~ $price;

This variant prints exactly the same string, but interpolation look more natural and easier to read. Note that the $ character was neither interpolated nor escaped in a single-quoted string: ' costs $'. That’s the main difference. Special characters in single quotes appear as-is.

Here is a few more special characters that have special meaning in double-quoted strings:

\$ Dollar sign
\n Newline
\r Carriage return
\t Horizontal tab
\" Double quote
\\ Backslash

The way you quote the string defines how Raku treats special characters. Consider these two examples:

say 'One\nTwo';
say "Three\nFour";

If you run this program, you will see that the first string appears as is on a single line. The second string was split into two pieces:


In double quotes, a special sequence \n was processed as a newline character, while in a string in single quotes it was a regular sequence of two characters: \ and n.

There’s an interesting exception for ' and \. In single quotes, you can escape a single quote by prefixing it with another \:

say '\''; # '

A backslash also has to be escaped if a single quote follows it:

say 'a\b\c\\'; # a\b\c\


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