在PHP中使用'func_get_arg'的好例子是什么?-Whatisthegoodexampleofusing'func_get_arg'inPHP?

22  

I usually use func_get_args() which is easier to use if wanting multiple arguments.

我通常使用func_get_args()，如果需要多个参数，则更容易使用。

For example, to recreate PHP's max().

例如，重新创建PHP的max()。

function max() {
   $max = -PHP_INT_MAX;
   foreach(func_get_args() as $arg) {
      if ($arg > $max) {
          $max = $arg;
      }
   }
   return $max;
}

CodePad.

CodePad。

Now you can do echo max(1,5,7,3) and get 7.

现在你可以做echo max(1,5,7,3)得到7。

2  

First of all, you are using the term "polymorphism" totally wrong. Polymorphism is a concept in object-oriented programming, and it has nothing to do with variable number of arguments in functions.

首先，您使用的术语“多态性”是完全错误的。多态性是面向对象编程中的一个概念，它与函数中的变量数量无关。

In my experience, all func_get_args allows you to do is add a little syntactic sugar.

在我的经验中，所有func_get_args允许您添加一点语法糖。

Think of a function that can take any number of integers and return their sum. (I 'm cheating, as this already exists in array_sum. But cheating is good if it keeps the example simple). You could do it this way:

考虑一个函数，它可以取任意数量的整数并返回它们的和。(我在作弊，因为这在array_sum中已经存在。但是作弊如果能保持简单的例子就很好)。你可以这样做:

// you can leave "array" out; I have it because we should be getting one here
function sum1(array $integers) {
    return array_sum($integers);
}

Now you would call this like so:

你可以这样称呼它:

$sum = sum1(array(1));
$sum = sum1(array(1, 2, 3, 4));

This isn't very pretty. But we can do better:

这不是很漂亮。但我们可以做得更好:

function sum2() {
    $integers = func_get_args();
    return array_sum($integers);
}

Now you can call it like this:

现在你可以这样称呼它:

$sum = sum2(1);
$sum = sum2(1, 2, 3, 4);

2  

Let's say we have multiple arrays containing data in which we need to search across the keys for their values without merging these arrays.

假设我们有多个数组，其中包含数据，我们需要跨键搜索它们的值，而不需要合并这些数组。

The arrays are like:

数组是:

$a = array('a' => 5, 'b' => 6);
$b = array('a' => 2, 'b' => 8);
$c = array('a' => 7, 'b' => 3);

In that case, say we need to get all the values of the key a from all the arrays. We can write a function that take in arbitrary number of arrays to search in.

在这种情况下，假设我们需要从所有数组中获取键a的所有值。我们可以编写一个函数，它接受任意数量的数组进行搜索。

// we need the key, and at least 1 array to search in
function simpleSearchArrays($key, $a1){
    $arrays = func_get_args();
    array_shift($arrays); // remove the first argument, which is the key
    $ret = array();
    foreach($arrays as $a){
        if(array_key_exists($key, $a)){
            $ret[] = $a[$key];
        }
    }
    return $ret;
}

So if we use the function:

如果我们使用这个函数

 $x = simpleSearchArrays('a', $a, $b, $c);

$x will then contain array(5, 2, 7).

$x将包含数组(5,2,7)。

1  

Personally, I don't think there is a good use case for it inside a normal function. As a control freak I like to know exactly what is being passed to my functions and I like to know exactly what I'm passing.

就我个人而言，我不认为在一个普通的函数中有一个很好的用例。作为一个控制狂，我喜欢确切地知道传递给我的函数的是什么，我喜欢确切地知道我传递的是什么。

However, it can be use full for things like Dynamic/Static URL routing. When you are rewriting (via mod_rewrite) the URL args to a single bootstrap.

但是，它可以完全用于动态/静态URL路由。当您重写(通过mod_rewrite) URL时，将args重写为一个引导程序。

In this sense, you can have arguments that don't necessarily need to exist with every page request.

在这个意义上，您可以拥有不必在每个页面请求中都存在的参数。

1  

I hardly ever use func_get_arg(), but I do use its cousin func_get_args() quite a bit. Here's one example, a function along the lines of the echo statement that entity encodes all its arguments:

我几乎不使用func_get_arg()，但我确实经常使用它的表亲func_get_args()。这里有一个例子，一个沿着echo语句的函数，实体会编码所有的参数:

function ee() {
    $args = func_get_args();
    echo implode('', array_map('htmlentities', $args));
}

I use that function quite a bit.

我经常用这个函数。

Here's another useful example, a function that does the same job as SQL's COALESCE() function.

下面是另一个有用的示例，该函数的工作与SQL的COALESCE()函数相同。

function coalesce() {
    $args = func_get_args();
    foreach ($args as $arg) {
        if (!is_null($arg)) {
            return $arg;
        }
    }
    return null;
}

It returns the first non-null argument passed in, or null if there's no such argument.

它返回传入的第一个非空参数，如果没有此类参数，则返回null。

0  

Read the official document and found that func_get_args():
Gets an array of the function's argument list.

阅读官方文档，发现func_get_args():获取函数的参数列表的数组。

This function may be used in conjunction with func_get_arg() and func_num_args() to allow user-defined functions to accept variable-length argument lists.

这个函数可以与func_get_arg()和func_num_args()一起使用，以允许用户定义的函数接受可变长度参数列表。

= 2) {
                echo "Second argument is: " . func_get_arg(1) . "\n";
            }
            $arg_list = func_get_args();
            for ($i = 0; $i <$numargs; $i++) {
                echo "Argument $i is: " . $arg_list[$i] . "\n";
            }
        }

        foo(1, 2, 3);
?>

0  

As of php5.6, there isn't a use case of func_get_arg anymore; which isn't to say that its functionality isn't needed anymore, but is replaced by the variadic function using the ... syntax:

从php5.6开始，就不再有func_get_arg的用例了;这并不是说它的功能不再需要了，而是用…语法:

/**
 * @param array $arguments
 */
public function poit(...$arguments)
{
     foreach($arguments as $argument) {
         ...
     }
}

This is especially useful if there are methods that are overloaded at the end; one does need to filter out the first arguments anymore, as showcased by an example:

如果有在最后重载的方法，这一点尤其有用;一个人需要过滤掉第一个参数，就像一个例子展示的那样:

Old style using func_get_arg:

使用func_get_arg旧风格:

function foo($a, $b) {
    $c = array();
    if (func_num_args() > 2) {
        for($i = 0; $i 

function foo($a, $b, …$c) {
    var_dump($a, $b, $c);
    // Do something
}
foo('a', 'b', 'c', 'd');