FAQ 4.49 How do I process/modify each element of an array?

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4.49: How do I process/modify each element of an array?

    Use "for"/"foreach":

            for (@lines) {
                    s/foo/bar/;     # change that word
                    tr/XZ/ZX/;      # swap those letters

    Here's another; let's compute spherical volumes:

            for (@volumes = @radii) {   # @volumes has changed parts
                    $_ **= 3;
                    $_ *= (4/3) * 3.14159;  # this will be constant folded

    which can also be done with "map()" which is made to transform one list
    into another:

            @volumes = map {$_ ** 3 * (4/3) * 3.14159} @radii;

    If you want to do the same thing to modify the values of the hash, you
    can use the "values" function. As of Perl 5.6 the values are not copied,
    so if you modify $orbit (in this case), you modify the value.

            for $orbit ( values %orbits ) {
                    ($orbit **= 3) *= (4/3) * 3.14159;

    Prior to perl 5.6 "values" returned copies of the values, so older perl
    code often contains constructions such as @orbits{keys %orbits} instead
    of "values %orbits" where the hash is to be modified.


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