sort

Sorts a list of values and returns them in sorted order.

Sorts the input list according to the comparison mode determined by the op’s private flags:

• Default (string): Lexicographic comparison via cmp.
• Numeric (OPpSORT_NUMERIC, 0x01): Floating-point comparison.
• Custom block (OPpSORT_BLOCK, 0x20): A CV on the stack is used as the comparator. $a and $b are set in the current package via cached cells and the CV is executed using the multicall pattern (pad + call frame set up once, only $a/$b updates per comparison) with a merge-sort algorithm.
• Descend (OPpSORT_DESCEND, 0x08): Reverses the final result.

Array arguments are flattened before sorting.

Synopsis

my @sorted = sort @list;                    # lexicographic
my @sorted = sort { $a <=> $b } @list;      # numeric
my @sorted = sort { $b cmp $a } @list;      # reverse lexicographic
my @sorted = sort \&compare, @list;          # named comparator

Implementation Notes

perl5 (pp_sort.c): OPpSORT_NUMERIC (0x01): use C-level numeric compare (detected at compile time) OPpSORT_DESCEND (0x08): reverse order OPpSORT_BLOCK (0x20): comparison sub on stack (custom comparator) Default (no flags): lexical string sort via sv_cmp

perl5 detects { $a <=> $b } at compile time (S_simplify_sort in op.c), sets OPpSORT_NUMERIC, and deletes the comparison block entirely. The sort then uses a C-level SvIV compare — zero sub calls.

See Also

PP runtime: sort | reverse, map, grep