Creating an empty array in PHP and later checking if it there is some valid elements at an index

Question

In Javascript I would do something like this-

var time_array = [];
if ((previousTime > time_array[i]) || (time_array[i] === undefined) )
{
     //Do Something
}

I want to do something similar in PHP

$time_array = array();
if (($previousTime> $time_array[$i]) || ($time_array[$i] === undefined) ))
{
    //Do Something

}

I can do this very easily in Javascript , but I am a little confused about it in PHP.

Ivan Kvasnica · Accepted Answer · 2016-11-16 15:07:16Z

1

$time_array = array();
if (!isset($time_array[$i]) || $previousTime > $time_array[$i])
{
    //Do Something

}

It will first check if the variable is set and if it is not, the second condition will never be evaluated, so it's safe to use.

Edit: isset() checks whether a variable is declared and is set to a non-null value. You may want to use: if ($time_array[$i] === null) instead (that would be probably more similar to JS's undefined).

answered Nov 16, 2016 at 15:07

Ivan Kvasnica

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3 Comments

user2506641 Over a year ago

if you have error_reporting(E_ALL) on, then php will notify you of the undefined index, when using if ($time_array[$i] === null), therefore I would suggest to not do that, and use isset() instead.

Ivan Kvasnica Over a year ago

That's true, my bad. Thank you for your comment, @Hallur

SMG Over a year ago

(!isset($time_array[$i]) || ($time_array[$i] === null) || ($previousTime > $time_array[$i])) - I did something like this and it works for me

user2693928 · Accepted Answer · 2016-11-16 15:03:15Z

0

Just use this: http://www.w3schools.com/php/func_array_key_exists.asp

if (array_key_exists($i,$time_array))
 {
     echo "Key exists!";
 }

answered Nov 16, 2016 at 15:03

user2693928

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