PHP explode and array index

How can I get the following code to work?

$a = explode('s', $str)[0];

I only se开发者_运维问答e solutions looking like this:

$a = explode('s', $str); $a=$a[0];

As others have said, PHP is unlike JavaScript in that it can't access array elements from function returns. The second method you listed works. You can also grab the first element of the array with the current(), reset(), or array_pop() functions like so:

$a = current( explode( 's', $str ) ); //or
$a = reset( explode( 's', $str ) ); //or
$a = array_pop ( explode( 's', $str ) );

If you would like to remove the slight overhead that explode may cause due to multiple separations, you can set its limit to 2 by passing two after the other arguments. You may also consider using str_pos and strstr instead:

$a = substr( $str, 0, strpos( $str, 's' ) );

Any of these choices will work.

EDIT Another way would be to use list() (see PHP doc). With it you can grab any element:

list( $first ) = explode( 's', $str ); //First
list( ,$second ) = explode( 's', $str ); //Second
list( ,,$third ) = explode( 's', $str ); //Third
//etc.

That not your style? You can always write a small helper function to grab elements from functions that return arrays:

function array_grab( $arr, $key ) { return( $arr[$key] ); }

$part = array_grab( explode( 's', $str ), 0 ); //Usage: 1st element, etc.

EDIT: PHP 5.4 will support array dereferencing, so you will be able to do:

$first_element = explode(',','A,B,C')[0];

You are correct with your second code-block. explode, and other functions can't return a fully formed array for immediate use,and so you have to set a temporary variable. There may be code in the development tree to do that, but the only way to get the elements you need for now, is the temporary variable.

use current

$a = current(explode('s', $str));

but I found is ugly

You can use this:

$a = array_shift(array_slice(explode("s", $str), 0, 1)));

This is the best way I have found to get a specific element from an array from explode.

Breakdown:

• Explode returns an array on delimiter
• array_slice($arrayname, $offset, $length) gives you a new array with all items from offset, lenght
• array_shift($array) gives you the first (and in this case, the only) item in the array passed to it.

This doesen't look pretty, but does the same as:

$a = explode('s', $str)[0];

There must be a better way to do this, but I have not found it.

Update: I was investigating this because I wanted to extract a portion of a URL, so i did the following tests:

function urlsplitTest() 
{

    $url = 'control_panel/deliveryaddress/188/edit/';
    $passes = 1000000;

    Timer::reset();
    Timer::start();
    $x =0;
    while ($x<$passes) {
        $res = array_shift(array_slice(explode("/", $url), 2, 1));
        $x++;
    }
    Timer::stop();
    $time = Timer::get();
    echo $res.'<br />Time used on: array_shift(array_slice(explode("/", $url), 2,     1)):'.$time;

    Timer::reset();
    Timer::start();
    $x =0;
    while ($x<$passes) {
        $res = array_get(explode("/", $url), 2);
        $x++;
    }
    Timer::stop();
    $time = Timer::get();
    echo $res.'<br />Time used on: array_get(explode("/", $url), 2): '.$time;

    Timer::reset();
    Timer::start();
    $x =0;
    while ($x<$passes) {
        $res = substr($url, 30, -6);
        $x++;
    }
    Timer::stop();
    $time = Timer::get();
    echo $res.'<br />Time used on: substr($url, 30, -6): '.$time;
}

function array_get($array, $pos) {return $array[$pos];}

The results were as following:

Time used on: array_shift(array_slice(explode("/", $url), 2, 1)):7.897379
Time used on: array_get(explode("/", $url), 2): 2.979483
Time used on: substr($url, 30, -6): 0.932806

In my case i wanted to get the number 188 from the url, and all the rest of the url was static, so i ended up using the substr method, but for a dynamic version where lenth may change, the array_get method above is the fastets and cleanest.