This is an automatically generated page and cannot be edited directly. Text in Composite pages, (URLs starting with 'routine' or 'syntax') can be edited by clicking on the link labeled 'in context', and editing the text there.

Exit this popup by pressing <Escape>, or clicking on X or on the background.

$_
Combined from primary sources listed below.

In Variables§

See primary documentation in context for The $ variable.

$_ is the topic variable. A fresh one is created in every block. It's also the default parameter for blocks that do not have an explicit signature, so constructs like for @array { ... } and given $var { ... } bind the value or values of the variable to $_ by invoking the block.

for <a b c> { say $_ }  # binds $_ to 'a', 'b' and 'c' in turn
say $_ for <a b c>;     # same, even though it's not a block
given 'a'   { say $_ }  # binds $_ to 'a'
say $_ given 'a';       # same, even though it's not a block

Because $_ is bound to the value of the iteration, you can also assign to $_ if it is bound to something assignable.

my @numbers = ^5;   # 0 through 4
$_++ for @numbers;  # increment all elements of @numbers
say @numbers;

# OUTPUT: «1 2 3 4 5␤»

CATCH blocks bind $_ to the exception that was caught. The ~~ smartmatch operator binds $_ on the right-hand side expression to the value of the left-hand side.

Calling a method on $_ can be shortened by leaving off the variable name:

.say;                   # same as $_.say

m/regex/ and /regex/ regex matches and s/regex/subst/ substitutions work on $_:

say "Looking for strings with non-alphabetic characters...";
for <ab:c d$e fgh ij*> {
    .say if m/<-alpha>/;
}

# OUTPUT: «Looking for strings with non-alphabetic characters...
#          ab:c
#          d$e
#          ij*␤»