How to check if a PHP array has any value set?

Question

I am working on a signup form, I am using PHP and on my processing part I run some code, if a submitted item fails I then add it to an errors array.

Below is a snip of the code, I am at the point where I need to find the best method to determine if I should trigger an error.

So if there is a value set in the error array then I need to redirect and do some other stuff.

I was thinking of using isset or else is_array but I don't think that is the answer since I set the array using **$signup_errors = array()** wouldn't this make the is_array be true?

Can anyone suggest a good way to do this?

//at the beginning I set the error array
$signup_errors = array();

// I then add items to the error array as needed like this...
$signup_errors['captcha'] = 'Please Enter the Correct Security Code';

Community · Accepted Answer · 2023-11-17 20:38:18Z

38

if ($signup_errors) {
  // there was an error
} else {
  // there wasn't
}

How does it work? When converting to boolean, an empty array converts to false. Every other array converts to true. From the PHP manual:

Converting to boolean

To explicitly convert a value to boolean, use the (bool) or (boolean) casts. However, in most cases the cast is unncecessary, since a value will be automatically converted if an operator, function or control structure requires a boolean argument.

See also Type Juggling.

When converting to boolean, the following values are considered FALSE:

the boolean FALSE itself

the integer 0 (zero)

the float 0.0 (zero)

the empty string, and the string "0"

an array with zero elements

an object with zero member variables (PHP 4 only)

the special type NULL (including unset variables)

SimpleXML objects created from empty tags

Every other value is considered TRUE (including any resource).

You could also use empty() as it has similar semantics.

edited Nov 17, 2023 at 20:38

CommunityBot

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answered Sep 3, 2009 at 2:52

cletus

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3 Comments

too much php Over a year ago

+1 I don't know why anyone would want to do anything more complicated than this ...

Corey Ballou Over a year ago

+1. Also good to note that empty() should be used if you cannot guarantee your variable has already been initialized (as in the case with $_POST data).

Progrock Over a year ago

@toomuchphp probably because if you are unfamiliar with Php's type juggling it's not immediately obvious.

gnarf · Accepted Answer · 2009-09-03 02:50:38Z

7

Perhaps empty()?

From Docs:

Return Values

Returns FALSE if var has a non-empty and non-zero value.

The following things are considered to be empty:
"" (an empty string)
0 (0 as an integer)
"0" (0 as a string)
NULL
FALSE
array() (an empty array)
var $var; (a variable declared, but without a value in a class)

answered Sep 3, 2009 at 2:50

gnarf

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Comments

Amber · Accepted Answer · 2009-09-03 02:51:26Z

4

Check if...

if(count($array) > 0) { ... }

...if it is, then at least one key-value pair is set.

Alternatively, check if the array is not empty():

if(!empty($array)) { ... }

answered Sep 3, 2009 at 2:51

Amber

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2 Comments

Szaman Over a year ago

since PHP7.2, using count() will throw an error if called on a non-countable object. so if your $array is null, this approach will not work.

globalSchmidt Over a year ago

Another use case where this will not work: if you use an array name for an input field (like <input type="text" name="myInputField[]">) for several items, then, when the form is submitted without any inputs, the $_POST will include an array like this: myInputField = [0 =>"", 1=>"", etc.]. Using count(), will get a count of the nodes, but there won't be any values. So a mere count() may give you false indication that there are values to be processed.

Progrock · Accepted Answer · 2021-05-25 11:13:50Z

3

Use array_filter if you already have keys, but want to check for non-boolean evaluated values.

<?php
$errors = ['foo' => '', 'bar' => null];
var_dump(array_filter($errors));

$errors = ['foo' => 'Oops', 'bar' => null];
var_dump(array_filter($errors));

Output:

array(0) {
}
array(1) {
  ["foo"]=>
  string(4) "Oops"
}

Use:

<?php
if(array_filter($errors)) {
    // Has errors
}

edited May 25, 2021 at 11:13

answered Jul 31, 2017 at 13:26

Progrock

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Comments

M Sandbergen · Accepted Answer · 2009-11-10 14:46:42Z

0

You could check on both the minimum and maximum values of the array, in this case you can have a large array filled with keys and empty values and you don't have to iterate through every key-value pair

if(!min($array) && !max($array)) { ... }

answered Nov 10, 2009 at 14:46

M Sandbergen

1

Comments

Anthony Rutledge · Accepted Answer · 2014-05-27 21:52:16Z

The language construct isset(), is for testing to see if variables and array elements are set and not NULL. Using is_array() would tell you if the argument you supply to it is an array. Thus, I do not think using isset() or is_array() would give you the correct and desired result that you are seeking.

The code:

$signup_errors = array();

means that ...

is_array($signup_errors);

would return true. However, this does not mean that the Boolean language rules of PHP would evaluate....

if($signup_errors)
{
     //*Do something if $signup_errors evaluates to true*;
}

as true, unless some elements are added to it. When you did this,

$signup_errors['captcha'] = 'Please Enter the Correct Security Code';

you fulfilled the PHP language requirement for the array above to evaluate to true. Now, if for some reason you wanted, or needed, to use isset() on the array elements in the future, you could. But, the conditional statement above is enough for you this case.

Progrock · Accepted Answer · 2020-02-21 10:51:05Z

0

I should add an obvious answer here. If you initialise your error array as an empty array. And later want to check if it is no longer an empty array:

<?php
$errors = [];

if($errors !== [])
{
    // We have errors.
}

answered Feb 21, 2020 at 10:51

Progrock

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