DB<123> $str = join "","a".."j"
 => "abcdefghij"

  DB<124> $x=0;$str =~ /(\w)(?{print "match ",++$x," $1 \n"})/g
match 1 a 
match 2 b 
match 3 c 
match 4 d 
match 5 e 
match 6 f 
match 7 g 
match 8 h 
match 9 i 
match 10 j 
 => ("a", "b", "c", "d", "e", "f", "g", "h", "i", "j")

  DB<125> $x=0; while ( $str =~ /(\w)/g ) {print "match ",++$x," $1 \n"}
match 1 a 
match 2 b 
match 3 c 
match 4 d 
match 5 e 
match 6 f 
match 7 g 
match 8 h 
match 9 i 
match 10 j 
 => ""