How to avoid undefined offset

Question

How can you easily avoid getting this error/notice:

Notice: Undefined offset: 1 in /var/www/page.php on line 149

... in this code:

Answer 1

Want to mention a more general utility function that I use since decades. It filters out empty values and trims spaces. It also uses array_pad() to make sure you get at least the requested amount of values (as suggested by @KingCrunch).

/**
 * Does string splitting with cleanup.
 * Added array_pad() to prevent list() complaining about undefined index
 * @param $sep string
 * @param $str string
 * @param null $max
 * @return array
 */
function trimExplode($sep, $str, $max = null)
{
    if ($max) {
        $parts = explode($sep, $str, $max); // checked by isset so NULL makes it 0
    } else {
        $parts = explode($sep, $str);
    }
    $parts = array_map('trim', $parts);
    $parts = array_filter($parts);
    $parts = array_values($parts);
    $parts = array_pad($parts, $max, null);
    return $parts;
}

Answer 2

I'd probably break this up into two steps

$split = explode('|', $value);
$func = $split[0];
if(count($split) > 1)
  $field = $split[1];
else
  $field = NULL;

There's probably a quicker and neater way though.

Answer 3

list($func, $field) = array_pad(explode('|', $value, 2), 2, null);

Two changes:

• It limits the size of the array returned by explode() to 2. It seems, that no more than this is wanted
• If there are fewer than two values returned, it appends null until the array contains 2 values. See Manual: array_pad() for further information

This means, if there is no | in $value, $field === null. Of course you can use every value you like to define as default for $field (instead of null). Its also possible to swap the behavior of $func and $field

list($func, $field) = array_pad(explode('|', $value, 2), -2, null);

Now $func is null, when there is no | in $value.

Answer 4

if (count(explode('|', $value))==2)
  list($func, $field) = explode('|', $value);

However it's slightly not optimal.

Answer 5

I often come across this issue, so I wanted a function that allowed something nicer syntactically without unnecessarily padding the array or string.

// Put array entries in variables. Undefined index defaults to null
function toVars($arr, &...$ret)
{
    $n = count($arr);
    foreach ($ret as $i => &$r) {
        $r = $i < $n ? $arr[$i] : null;
    }
}

// Example usage
toVars(explode('|', $value), $func, $field);

For my purposes, I'm usually working with an array, but you could write a similar function that includes the explode function, like this...

// Explode and put entries in variables. Undefined index defaults to null
function explodeTo($delimiter, $s, &...$ret)
{
    $arr = explode($delimier, $s);
    $n = count($arr);
    foreach ($ret as $i => &$r) {
        $r = $i < $n ? $arr[$i] : null;
    }
}

// Example usage
toVars('|', $value, $func, $field);

Requires PHP5.6 or above for variadic function: http://php.net/manual/en/functions.arguments.php#functions.variable-arg-list

Answer 6

This worked for me:

@list($func, $field) = explode('|', $value);