Perl Style: Use foreach() Loops

Jan 1, 1998 by Tom Christiansen

• A foreach loop’s implicit aliasing and localizing can make for a powerful construct:

      foreach $e (@a, @b) { $e *= 3.14159 }
  
      for (@lines) {
          chomp;
          s/fred/barney/g;
          tr[a-z][A-Z];
      }
  

• Remember you can copy and modify all at once:

      foreach $n (@square = @single) { $n **= 2 }
  

• You can use hash slices to modify hash values, too:

      # trim whitespace in the scalar, the array,
      # and all the values in the hash
      foreach ($scalar, @array, @hash{keys %hash}) {
          s/^\s+//;
          s/\s+$//;
      }
  

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Copyright © 1998, Tom Christiansen All rights reserved.