PHP test for empty and/or null and/or unset array

Question

I want to keep this short. I don't know if I have the terminology correct, but I got this example from the Codeigniter handbook Vol.1.

if (count($args) > 1 || is_array($args[0]))

I've run into this problem numerous times. Depending on the datatype different tests are more appropriate. Some tests will just fail in unexpected ways.

How does one determine the most appropriate, and possibly, the most concise test?

Just to be clear I'm looking for the most effective way to test if an object/variable is ready to use, regardless of the datatype, if that's possible.

Also I don't want the solution to apply merely to lists like in the example. It should be widely applicable.

Shakti Singh · Accepted Answer · 2012-10-28 05:09:53Z

6

Just use empty

if(!empty($args)){
  echo 'Array is set, not empty and not null';
}

answered Oct 28, 2012 at 5:09

Shakti Singh

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4 Comments

noel Over a year ago

This couldn't be used if the variable happened to be a string right?

Shakti Singh Over a year ago

@shakabra: Why not?, you could.

Matthew Blancarte Over a year ago

empty() will check for empty strings, too. @shakabra you should take a good look at the manual page that was linked. It spells out exactly what the function does.

noel Over a year ago

Ok I don't know why I haven't used this more often. Thanks for the answer. But will empty() work with database resources if I'm using MySQL. That's been a real headache for me.

interskh · Accepted Answer · 2012-10-28 05:08:29Z

1

use empty() bool empty ( mixed $var )

http://www.php.net/manual/en/function.empty.php

Determine whether a variable is considered to be empty. A variable is considered empty if it does not exist or if its value equals FALSE. empty() does not generate a warning if the variable does not exist.

answered Oct 28, 2012 at 5:08

interskh

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4 Comments

noel Over a year ago

That's not PHP and it doesn't get anywhere close to covering all the use cases in my example.

interskh Over a year ago

@shakabra yes it is php, i should've included the link to manual page: php.net/manual/en/function.empty.php

interskh Over a year ago

@shakabra your example is also a bit different, it not only checks if $args has more than one element but also checks if $args[0] (the first element of $args) is an array as well

noel Over a year ago

Sorry it was just a line of code that got me thinking about previous problems.

Jonathan Roy · Accepted Answer · 2012-10-28 05:30:20Z

0

I've been using the following function for a while.

You can add your own test for all possible variable types.

function is_valid_var($var)
{
  if ( isset( $var ) ) {

    // string
    if ( is_string( $var ) && strlen( $var ) == 0 ) return false;

    // array
    elseif ( is_array( $var ) && count( $var ) == 0 ) return false;

    // unknown
    else return true;
  }

  return false;
}

answered Oct 28, 2012 at 5:30

Jonathan Roy

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