grep BLOCK LIST
grep EXPR,LIST
     This is similar in spirit to, but not the same as,
     grep(1) and its relatives.  In particular, it is
     not limited to using regular expressions.

     Evaluates the BLOCK or EXPR for each element of
     LIST (locally setting "$_" to each element) and
     returns the list value consisting of those 
     ele­ments for which the expression evaluated to true.
     In scalar context, returns the number of times the
     expression was true.

     @foo = grep(!/^#/, @bar);    # weed out comments

     or equivalently,

     @foo = grep {!/^#/} @bar;    # weed out comments