PHP函数的数据分析函数

$numbers = array(1, 2, 3, 4, 5);
echo count($numbers); // 输出 5

$numbers = array(1, 2, 3, 4, 5);
echo array_sum($numbers); // 输出 15

$numbers = array(1, 2, 3, 4, 5);
echo array_sum($numbers) / count($numbers); // 输出 3

$numbers = array(5, 4, 3, 2, 1);
sort($numbers);
print_r($numbers); // 输出Array ( [0] => 1 [1] => 2 [2] => 3 [3] => 4 [4] => 5 )

$numbers = array(1, 2, 3, 4, 5);
rsort($numbers);
print_r($numbers); // 输出Array ( [0] => 5 [1] => 4 [2] => 3 [3] => 2 [4] => 1 )

$numbers = array(1, 2, 3, 4, 5);
$new_numbers = array_filter($numbers, function($value) {
    return $value % 2 == 0; // 只保留偶数
});
print_r($new_numbers); // 输出Array ( [1] => 2 [3] => 4 )

$employees = array(
    array('name' => '张三', 'age' => 25, 'gender' => '男'),
    array('name' => '李四', 'age' => 30, 'gender' => '女'),
    array('name' => '王五', 'age' => 35, 'gender' => '男')
);
$new_employees = array_filter($employees, function($employee) {
    return $employee['gender'] == '男'; // 只保留男员工
});
print_r($new_employees); // 输出Array ( [0] => Array ( [name] => 张三 [age] => 25 [gender] => 男 ) [2] => Array ( [name] => 王五 [age] => 35 [gender] => 男 ) )

$numbers = array(1, 2, 1, 3, 2, 4, 5);
$new_numbers = array_unique($numbers);
print_r($new_numbers); // 输出Array ( [0] => 1 [1] => 2 [3] => 3 [5] => 4 [6] => 5 )

$string = 'Hello world';
echo strlen($string); // 输出 11

$string = 'Hello world';
echo strpos($string, 'o'); // 输出 4

$string = 'Hello world';
echo substr($string, 6, 5); // 输出 world