使用位操作: 在此方法中，您将找到带有1的数字的逐位与。如果位与为1，则该数字为奇数，否则为偶数。

function odd($var){
    return $var & 1;
}
function even($var){
    return !($var&1);
}
$arr = range(1,10);

echo "Odd Numbers: ";
echo "<pre>";
    print_r(array_filter($arr2, 'odd'));
echo "<pre>";

echo "<br>Even Numbers: ";
echo "<pre>";
    print_r(array_filter($arr2, 'even'));
echo "</pre>";

输出将是:

Odd Numbers:
Array
(
    [0] => 1
    [2] => 3
    [4] => 5
    [6] => 7
    [8] => 9
)

Even Numbers: 
Array
(
    [1] => 2
    [3] => 4
    [5] => 6
    [7] => 8
    [9] => 10
)

我做了一些测试，发现在mod, is_int和&-操作符之间，mod是最快的，紧随其后的是&-操作符。 Is_int几乎比mod慢4倍。

I used the following code for testing purposes: $number = 13; $before = microtime(true); for ($i=0; $i<100000; $i++) { $test = ($number%2?true:false); } $after = microtime(true); echo $after-$before." seconds mod<br>"; $before = microtime(true); for ($i=0; $i<100000; $i++) { $test = (!is_int($number/2)?true:false); } $after = microtime(true); echo $after-$before." seconds is_int<br>"; $before = microtime(true); for ($i=0; $i<100000; $i++) { $test = ($number&1?true:false); } $after = microtime(true); echo $after-$before." seconds & operator<br>"; The results I got were pretty consistent. Here's a sample: 0.041879177093506 seconds mod 0.15969395637512 seconds is_int 0.044223070144653 seconds & operator

虽然所有的答案都是正确的，但简单的解决方法是:

$check = 9;

:

echo ($check & 1 ? 'Odd' : 'Even');

or:

echo ($check % 2 ? 'Odd' : 'Even');

工作得很好。

使用位操作: 在此方法中，您将找到带有1的数字的逐位与。如果位与为1，则该数字为奇数，否则为偶数。

function odd($var){
    return $var & 1;
}
function even($var){
    return !($var&1);
}
$arr = range(1,10);

echo "Odd Numbers: ";
echo "<pre>";
    print_r(array_filter($arr2, 'odd'));
echo "<pre>";

echo "<br>Even Numbers: ";
echo "<pre>";
    print_r(array_filter($arr2, 'even'));
echo "</pre>";

输出将是:

Odd Numbers:
Array
(
    [0] => 1
    [2] => 3
    [4] => 5
    [6] => 7
    [8] => 9
)

Even Numbers: 
Array
(
    [1] => 2
    [3] => 4
    [5] => 6
    [7] => 8
    [9] => 10
)

是的，使用mod

$even = ($num % 2 == 0);
$odd = ($num % 2 != 0);

$before = microtime(true);

$n = 1000;  
$numbers = range(1,$n);

$cube_numbers = array_map('cube',$numbers);

function cube($n){      
    $msg ='even';       
    if($n%2 !=0){
        $msg = 'odd';
    }               
    return "The Number is $n is ".$msg;
}

foreach($cube_numbers as $cube){
    echo $cube . "<br/>";
}

$after = microtime(true);

echo $after-$before. 'seconds';