PHP | check if a number is Even or Odd

A number is called even if the number is divisible by 2 and is called odd if it is not divisible by 2. Given a number, we need to check whether it is odd or even in PHP.

Examples :

Input : 42
Output : Even
Explanation: The number 42 is divisible by 2

Input : 39
Output : Odd
Explanation: The number 39 is not divisible by 2

We can solve this problem in two different ways as described below:

1. Using modulo (%) operator: This is the simplest method of checking for even and odd and in this method, we simply check whether the number is divisible by 2 or not using the modulo ‘%’ operator.

   Below program explains the above approach:

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   <?php // PHP code to check whether the number  // is Even or Odd in Normal way function check($number){     if($number % 2 == 0){         echo "Even";      }     else{         echo "Odd";     } }    // Driver Code $number = 39; check($number) ?>

   Output :

   Odd
   

   Time Complexity: O(1)

2. Recursive method: In the recursive approach, we reduce the number by 2 in each recursive call. If the final number is 0 then its even or else it is 1, the result will be odd.
   Below is the implementation of above approach:

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   <?php // Recursive function to check whether // the number is Even or Odd  function check($number){     if($number == 0)         return 1;     else if($number == 1)         return 0;     else if($number<0)         return check(-$number);     else         return check($number-2);         }    // Driver Code $number = 39; if(check($number))     echo "Even"; else     echo "Odd"; ?>

   Output :

   Odd
   

   Time Complexity: O(n)

3. Using Bit Manipulation:
   In this method we will find bit-wise AND of the number with 1. If the bit-wise AND is 1, then the number is odd, else even.

   Below is the implementation of above idea.

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   <?php // PHP code to check whether the number  // is Even or Odd using Bitwise Operator function check($number) {            // One     $one = 1;            // Bitwise AND     $bitwiseAnd = $number & $one;            if($bitwiseAnd == 1)     {         echo "Odd";      }     else{         echo "Even";     } }    // Driver Code $number = 39; check($number) ?>

   Output :

   Odd
   

   Time Complexity: O(1)

PHP is a server-side scripting language designed specifically for web development. You can learn PHP from the ground up by following this PHP Tutorial and PHP Examples.