<?php for ($n=1, $k=1; $n<10, $k<10; $n++, $k++, $f=$n*$k) { echo "$n x $k = $f \n"; }
Standard input is empty
1 x 1 = 2 x 2 = 4 3 x 3 = 9 4 x 4 = 16 5 x 5 = 25 6 x 6 = 36 7 x 7 = 49 8 x 8 = 64 9 x 9 = 81
PHP Notice: Undefined variable: f in /home/rh2FAI/prog.php on line 4