Documentation for routine ++ assembled from the following types:

language documentation Operators

From Operators

(Operators) prefix ++

multi sub prefix:<++>($x is rw) is assoc<non>

This is the . Increments its argument by one and returns the updated value.

my $x = 3;
say ++$x;   # OUTPUT: «4␤» 
say $x;     # OUTPUT: «4␤»

It works by calling the succ method (for successor) on its argument, which gives custom types the freedom to implement their own increment semantics.

language documentation Operators

From Operators

(Operators) postfix ++

multi sub postfix:<++>($x is rw) is assoc<non>

Increments its argument by one and returns the original value.

my $x = 3;
say $x++;   # OUTPUT: «3␤» 
say $x;     # OUTPUT: «4␤»

It works by calling the succ method (for successor) on its argument, which gives custom types the freedom to implement their own increment semantics.

Note that this does not necessarily return its argument; e.g., for undefined values, it returns 0:

my $x;
say $x++;   # OUTPUT: «0␤» 
say $x;     # OUTPUT: «1␤»

Increment on Str will increment the number part of a string and assign the resulting string to the container. A is rw-container is required.

my $filename = "somefile-001.txt";
say $filename++ for 1..3;
# OUTPUT: «somefile-001.txt␤somefile-002.txt␤somefile-003.txt␤»