PHP 函数的函数指针用于解决哪些具体问题？

<?php

// 回调函数

function greet($name) {

echo “Hello, $name!\系统开发mhkj33n”;

}

// 调用回调函数

call_user_func(greet, John); // 输出：Hello, John!

?>

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<?php

class MyClass {

// 添加事件监听器

public function addEventListener($event, $listener) {

$this->listeners[$event][] = $listener;

}

// 触发事件

public function triggerEvent($event, $args) {

foreach ($this->listeners[$系统开发mhkj33event] ?? [] as $listener) {

call_user_func($listener, $args);

}

}

}

$obj = new MyClass();

$obj->addEventListener(click, function() { echo Click event triggered!\n; });

$obj->triggerEvent(click); // 输出：Click event triggered!

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<?php

// 比较函数

function compareAge($person1, $系统开发mhkj33person2) {

return $person1[age] – $person2[age];

}

// 对数组按年龄排序

$people = [

[name => John, age => 30],

[name => Mary, age => 25],

[name => Bob, age => 35],

];

usort($people, compareAge);

// 输出排序后的数组

foreach ($people as $person) {

echo $person[name] . : . $person[age] . “\n”;

}

?>

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