Hi,

Use Array Reference.

$file='
level 1
section1
section2
level 2
section3
section4
level 2
';

while ($file=~s#(level [0-9].+?)(level [0-9])#$2#s)
{
    $a=$1;

    @b=$a=~m#(section[0-9])#g;
    push (@array, [@b])
}
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