PHP check if a number is Even or Odd

Checking if a number is even or odd involves determining whether the number is divisible by 2. An even number has no remainder when divided by 2, while an odd number has a remainder of 1. This can be done using various methods like modulo or bit manipulation.

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:

Using modulo (%) operator

The modulo (%) operator checks if a number is even or odd by dividing it by 2 and examining the remainder. If the remainder is 0, the number is even; if the remainder is not 0 (1), the number is odd.

Example: In this example we defines a function check() to determine if a number is even or odd. It checks the remainder when divided by 2, and prints "Even" or "Odd." PHP

</p><pre><code class="language-php"><?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)
?></code></pre><div class="code-output"><br><strong>Output</strong><pre>Odd
</pre></div><span>
</span><b><strong>Time Complexity</strong></b><span>: O(1) </span><p></p><h2 id="recursive-method"><b><strong>Recursive method</strong></b></h2><p dir="ltr"><span>The recursive approach checks if a number is even or odd by repeatedly subtracting 2 from the number in each recursive call. If the number reaches 0, it's even; if it reaches 1, it's odd. </span></p><p dir="ltr"><b><strong>Example:</strong></b><span> In this example we use recursive function check() to determine if a number is even or odd by subtracting 2 until it reaches 0 (even) or 1 (odd), handling negative numbers as well.</span></p><p dir="ltr"><gfg-tabs data-run-ide="true" data-mode="light"><gfg-tab slot="tab">PHP

<?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";
?>

Using Bit Manipulation:

Using bit manipulation, you can check if a number is even or odd in PHP by examining the least significant bit. If number & 1 equals 0, the number is even; if it equals 1, the number is odd.

Example: In this example we checks if a number is even or odd using bitwise AND (&). It compares the number's least significant bit with 1; if true, it's odd; otherwise, it's even.PHP

<?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)
?>

Odd

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