如何在 PHP 中获取数组的第一个元素

### Answer: Use the PHP array_values() Function
If you know the exact index or key of an array you can easily get the first element, like this:

```php
<?php
// A sample indexed array
$cities = array("London", "Paris", "New York");
echo $cities[0]; // Outputs: London
 
// A sample associative array
$fruits = array("a" => "Apple", "b" => "Ball", "c" => "Cat");
echo $fruits["a"]; // Outputs: Apple
?>
```
However, there are certain situations where you don't know the exact index or key of the first element. In that case you can use the `array_values()` function which returns all the values from the array and indexes the array numerically, as shown in the following example:

```php
<?php
$arr = array(3 => "Apple", 5 => "Ball", 11 => "Cat");
echo array_values($arr)[0]; // Outputs: Apple
?>
```

Alternativly, you can also use the `reset()` function to get the first element.

The `reset()` function set the internal pointer of an array to its first element and returns the value of the first array element, or `FALSE` if the array is empty.

You can also use the `current()` function to get the first element of an array. This function returns the current element in an array, which is the first element by default unless you've re-positioned the array pointer, otherwise use the `reset()` function. Here's an example:

```php
<?php
$arr = array(3 => "Apple", 5 => "Ball", 11 => "Cat");
echo current($arr); // Outputs: Apple
echo reset($arr); // Outputs: Apple
echo next($arr); // Outputs: Ball
echo current($arr); // Outputs: Ball
echo reset($arr); // Outputs: Apple
?>
```