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Sanjib Sinha

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About Sanjib Sinha

  • Rank
    Regular Member
  • Birthday 07/18/1965

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  • Website URL
    http://sanjib.me

Profile Information

  • Gender
    Male
  • Location
    Kolkata
  • Interests
    story telling, web programming
  • Age
    49
  1. Thanks IThinkMyBrainHurtsI guessed something like this. But why should I go for such complexity? Please consider this code to test the primality: function is_prime($num) { for($i=2; $i<= (int)sqrt($num); $i++){ if($num % $i == 0) { return false; } } return true; } if(is_prime(119)){ echo 'Prime'; } else { echo 'Not Prime'; } //output not prime
  2. I had searched web and found some of them very interesting and few of them seem complex like this one in wiki: function isPrime($n) { if ($n <= 3) { return $n > 1; } else if ($n % 2 === 0 || $n % 3 === 0) { return false; } else { for ($i = 5; $i * $i <= $n; $i += 6) { if ($n % $i === 0 || $n % ($i + 2) === 0) { return false; } } return true; } } Specially this part: for ($i = 5; $i * $i <= $n; $i += 6) { if ($n % $i === 0 || $n % ($i + 2) === 0) { return false; } } It started from 5. It is okay. But the logic flow seems pretty complex. Can anyone translate in simple English actually what is happening?
  3. I have written a function to check whether any number is prime or not. Is it okay? or I can better it by any means? function isPrime($num){ $number = array(); for ($i=2; $i <= $num; $i++){ if(($num%2)==0){ continue; } if (($num%$i)==0){ break; } $number[]=$i; } /* * how I back calculate to make it successful foreach ($number as $key => $value) { echo "$key = $value <br>"; } echo count($number); */ if (count($number)== ($num-2)) { echo 'it is prime'; } else { echo 'not prime'; } } isPrime(101112345909);
  4. Yes, I am agreed with Adam. To start with and getting acquainted with the MVC approach, CodeIgniter is fine. Hopefully it will catch up with the advancement taking place in the PHP world; but, till then you can start with CI.
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