The meaning of PHP closure function
This article mainly introduces the PHP closure function in detail. The closure function does not have a function name. When the variable is passed in to function() and it can be used, the defined variable is treated as a function. For PHP closure Friends who are interested in functions can refer to
Anonymous function Also called closure function (closure allows the creation of a function without specifying a function, and is most often used as the value of a callback function parameter.
echo preg_replace_callback('~-([a-z])~', function ($match) {
return strtoupper($match[1]);
}, 'hello-world');`use use
$message = 'hello';
$example = function() use ($message){
var_dump($message);
};
echo $example();
//输出hello
$message = 'world';
//输出hello 因为继承变量的值的时候是函数定义的时候而不是 函数被调用的时候
echo $example();
//重置为hello
$message = 'hello';
//此处传引用
$example = function() use(&$message){
var_dump($message);
};
echo $example();
//输出hello
$message = 'world';
echo $example();
//此处输出world
//闭包函数也用于正常的传值
$message = 'hello';
$example = function ($data) use ($message){
return "{$data},{$message}";
};
echo $example('world');example
class Cart{
//在类里面定义常量用 const 关键字，而不是通常的 define() 函数。
const PRICE_BUTTER = 1.00;
const PRICE_MILK = 3.00;
const PRICE_EGGS = 6.95;
protected $products = [];
public function add($product,$quantity){
$this->products[$product] = $quantity;
}
public function getQuantity($product){
//是否定义了
return isset($this->products[$product])?$this->products[$product]:FALSE;
}
public function getTotal($tax){
$total = 0.0;
$callback = function($quantity,$product) use ($tax , &$total){
//constant 返回常量的值
//__class__返回类名
$price = constant(__CLASS__."::PRICE_".strtoupper($product));
$total += ($price * $quantity)*($tax+1.0);
};
//array_walk() 函数对数组中的每个元素应用用户自定义函数。在函数中，数组的键名和键值是参数
array_walk($this->products,$callback);
//回调匿名函数
return round($total,2);
}
}
$my_cart = new Cart();
$my_cart->add('butter',1);
$my_cart->add('milk',3);
$my_cart->add('eggs',6);
print($my_cart->getTotal(0.05));Summary: That’s it The entire content of the article, I hope it can be helpful to everyone’s study.
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