Apr 20th, 2014 at 03:59 PM

PHP Fibonacci Series printing

A Fibonacci Series of numbers will look like 0 , 1 , 1 , 2 , 3 , 5 , 8 , 13 , 21 , 34 , 55 First two Fibonacci numbers are 0 and 1 . After that each number will be the sum of previous two numbers . Here we can see that third Fibonacci number is 1 ( sum of first two numbers 0 + 1 ) , and fourth Fibonacci number will be the sum of third and second number ( 1 + 1 = 2 ) , and fifth Fibonacci number will be the sum of fourth and third number ( 2 + 1 = 3 ). The series will go like that infinity . Fibonacci number using recursion

function fibonacci($n){ 
    $iResult = 1; 
	
    if ($n == 0){ 
        $iResult = 0; 
    }else if ($n >= 2){ 
        $iResult = fibonacci($n - 1) + fibonacci($n - 2); 
    }else if ($n < 0){ 
        $iResult = -1; 
    } 

    return $iResult; 
}

//---print fibonacci sequence length 10
for($i=0;$i<=10;$i++){
  echo fibonacci($i).",";
}

Fibonacci number without using recursion

function fibonacci($n) {

 if($n <0)return -1;
 if ($n == 0)return 0;
 if($n == 1 || $n == 2)return 1;

 $int1 = 1;
 $int2 = 1;

 $fib = 0;

//start from n==3
 for($i=1; $i<=$n-2; $i++ ){
   $fib = $int1 + $int2;
   //swap the values out:
   $int2 = $int1;
   $int1 = $fib;
 }

return $fib;
}

//---print fibonacci sequence length 10
for($i=0;$i<=10;$i++){
  echo fibonacci($i).",";
}