Steps to convert a decimal number to octal number:
1. Take modulas(%) of decimal number by 8.
2. Now divide decimal number by 8.
3. Repeat these steps until condition matches.
4. Now reverse that number.
Go through the code given below.
<?php
     $numberToConvert = 78;
     if($numberToConvert > 0){
           $tempArray = array();
           echo "Octal of $numberToConvert is : ";
           while($numberToConvert){
               $tempArray[] = $numberToConvert%8;
               $numberToConvert = (int)($numberToConvert/8);
           }
           for($i = count($tempArray); $i >=0; $i--){
               echo $tempArray[$i];
           }       
     }else{
           echo 'Number should be greater then zero.';
     }
?>

