grep(EXPR,LIST)

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

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

             Note that, since $_ is a reference  into  the  array
             value,  it can be used to modify the elements of the
             array.  While this is useful and supported,  it  can
             cause  bizarre  results  if  the LIST is not a named
             array.