One of my colleges seem to have an 'undefined index' error on a code I wrote
This code of mine looks like this:
if ( is_array ($arr['key']))
My intention was to check whether $arr has a key named 'key', and if the value of that key is array itself. Should I do instead: if( isset($arr['key']) && is_array ($arr['key'])) ?
Maybe the following is equivavlent: Let's assume $var is not set. Then, will is_array($var) cause an error or will it just return false?
Thank you
Yes, use isset, then is_array.
if(isset($arr['key']) && is_array($arr['key'])) {
// ...
}
Because PHP uses short-circuit logic evaluation, it will stop before it gets to is_array(), so you'll never get an error.
Try:
is_array($arr) && array_key_exists('key', $arr)
check if it exists first, then if its an array. Otherwise you will still get the same error.
if ( isset($arr['key'])) {
if (is_array ($arr['key']) {
}
}
Maybe you can consider a generic get() function for safe-retrieving data from arrays:
/*
Get with safety
@author: boctulus
@param array
@param index1
@param index2
..
*/
function get(){
$numargs = func_num_args();
$arg_list = func_get_args();
$v = $arg_list[0];
for ($i = 1; $i < $numargs; $i++)
{
if (isset($v[$arg_list[$i]]))
$v = $v[$arg_list[$i]];
else
return null;
}
return $v;
}
Use:
$arr = [];
var_dump( get($arr,'a','b') ); // NULL
$arr['a']['b'] = 'ab';
var_dump( get($arr,'a','b') ); // 'ab'
