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10.5. Passing Arrays and Hashes by ReferenceProblemYou want to pass a function more than one array or hash and have each remain distinct. For example, you want to put the "Find elements in one array but not in another" algorithm from Recipe 4.7 in a subroutine. This subroutine must then be called with two arrays that remain distinct. SolutionPass arrays and hashes by reference, using the backslash operator: array_diff( \@array1, \@array2 ); DiscussionSee Chapter 11, References and Records, for more about manipulation of references. Here's a subroutine that takes array references and a subroutine call that generates them: @a = (1, 2);
@b = (5, 8);
@c = add_vecpair( \@a, \@b );
print "@c\n";
A potential difficulty with this function is that it doesn't check to make sure it got exactly two arguments that were both array references. You could check explicitly this way: unless (@_ == 2 && ref($x) eq 'ARRAY' && ref($y) eq 'ARRAY') { die "usage: add_vecpair ARRAYREF1 ARRAYREF2"; } If all you plan to do is See AlsoThe section on "Passing References" in Chapter 2 of Programming Perl and on "Pass by Reference" in perlsub (1); the section on "Prototypes" in Chapter 2 of Programming Perl or in perlsub (1); Recipe 10.11; Chapter 11; Chapter 4 of Programming Perl. |