How to avoid undefined index

How can you easily avoid getting this error/notice in PHP?

Notice: Undefin开发者_StackOverflow社区ed index: test in /var/www/page.php on line 21

The code:

$table = 'test';
$preset = array();
method($preset[$table]);

The array $preset exists but not with the specified index

Check if it exists using array_key_exists:

$table = 'test';
$preset = array();
if(array_key_exists($table, $preset)) {
    method($preset[$table]);
}else{
    // $table doesn't exist in $preset
}

Alternatively, you could use isset:

$table = 'test';
$preset = array();
if(isset($preset[$table])) {
    method($preset[$table]);
}else{
    // $table doesn't exist in $preset
}

Use if (isset($preset[$table]))

Or you can check first if key exists by using isset().

if ( isset($preset[$table]) )

Return true if exists, otherwise return false.