Question

How to multiply two numbers recursively without using multiplication, division, bitwise and loops in PHP

Answer 1

echo "3 * 7 = " . multiply(3, 7) . "<br />";
echo "3 * 0 = " . multiply(3, 0) . "<br />";
echo "0 * 3 = " . multiply(0, 3) . "<br />";
echo "3 * -5 = " . multiply(3, -5) . "<br />";
echo "-3 * 6 = " . multiply(-3, 6) . "<br />";

function multiply($x, $y)
{
    if ($y > 0)
        return ($x + multiply($x, $y - 1));
   
    if ($y < 0)
        return -multiply($x, -$y);
      
    return 0;
}
 
/*
run:
  
3 * 7 = 21
3 * 0 = 0
0 * 3 = 0
3 * -5 = -15
-3 * 6 = -18
   
*/

 

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