$ perl -del DB<1> x 0+( () = join('','','x'x(1<<30),'') =~ m{}g ) 0 1 DB<2> x 0+( () = join('','','x'x(1<<31),'') =~ m{}g ) 0 0 DB<3> x 0+( () = join('','','x'x((1<<31)-8),'') =~ m{}g ) 0 1 DB<4> x 0+( () = join('','','x'x((1<<31)-7),'') =~ m{}g ) 0 0 #### $ perl -del DB<2> x 0+( () = join('',('','x'x((1<<30)-10),'')x2) =~ m{}g ) 0 2 DB<1> x 0+( () = join('',('','x'x((1<<30)-10),'')x3) =~ m{}g ) 0 0 #### $ perl -del DB<1> $x = join('',('','x'x((1<<30)-10),'')x2); while( $x =~ m{}g ) { print pos($x), $/ } 1073741821 2147483642 DB<1> $x = join('',('','x'x((1<<30)-10),'')x3); while( $x =~ m{}g ) { print pos($x), $/ } DB<2>