> perldoc -f splice
splice ARRAY,OFFSET,LENGTH,LIST
splice ARRAY,OFFSET,LENGTH
splice ARRAY,OFFSET
splice ARRAY
Removes the elements designated by OFFSET and LENGTH from an
array, and replaces them with the elements of LIST, if any. In
list context, returns the elements removed from the array. In
scalar context, returns the last element removed, or "undef" if
no elements are removed. The array grows or shrinks as
necessary. If OFFSET is negative then it starts that far from
the end of the array. If LENGTH is omitted, removes everything
from OFFSET onward. If LENGTH is negative, removes the elements
from OFFSET onward except for -LENGTH elements at the end of the
array. If both OFFSET and LENGTH are omitted, removes
everything. If OFFSET is past the end of the array, perl issues
a warning, and splices at the end of the array.
The following equivalences hold (assuming "$[ == 0"):
push(@a,$x,$y) splice(@a,@a,0,$x,$y)
pop(@a) splice(@a,-1)
shift(@a) splice(@a,0,1)
unshift(@a,$x,$y) splice(@a,0,0,$x,$y)
$a[$x] = $y splice(@a,$x,1,$y)
Example, assuming array lengths are passed before arrays:
sub aeq { # compare two list values
my(@a) = splice(@_,0,shift);
my(@b) = splice(@_,0,shift);
return 0 unless @a == @b; # same len?
while (@a) {
return 0 if pop(@a) ne pop(@b);
}
return 1;
}
if (&aeq($len,@foo[1..$len],0+@bar,@bar)) { ... }