CODEWITHSUNDEEP
phpisset
Martin Currah
Martin Currah

Reputation: 517

isset strange behaviour and handling function returned data

Could anyone please explain to me why the following line of code prints out true?

$a = "string";

if(isset($a['error'])) echo true; else echo false;

When I do a function call, I return the expected data if it worked properly, or return array("error" => $error);

Then on receiving the returned data I check if isset($var['error']) and if its not then I know I received some expected data.

I would also appreciate if you could advice me if this a good or bad way of handling data between function calls? And if there is a better "good practice" for this.

Upvotes: 1

Views: 116

Answers (3)

Lix
Lix

Reputation: 47956

I'm not 100% sure why the behavior is like this, but I do know that PHP allows you to handle strings in a similar way as an array.

$a = "StackOverflow";

echo $a[2]; // a
echo $a[4]; // k
echo $a[6]; // v
echo $a[8]; // r

Now when you pass a string key as an index of the array, PHP will try to parse that string into a numerical value to use as a key.

echo $a['stack']; // S
echo $a['over']; // S
echo $a['flow']; // S

echo $a['0stack']; // S
echo $a['1over']; // t
echo $a['2flow']; // a
echo $a['3flow']; // c
echo $a['4flow']; // k

Upvotes: 0

Your Common Sense
Your Common Sense

Reputation: 157839

Well, this is some of PHP misbehaviors, which luckily has been fixed in some recent version.

You can address a single character in a string using the same square braces used to address an array element.

'error' evaluates to 0 and then you have got $a[0] which is set.

to fix that you have to check if $a is array first

Upvotes: 3

Peter
Peter

Reputation: 16923

I believe it's a bug and it's fixed in PHP 5.4+: http://codepad.viper-7.com/fz1rnT

looks like isset($str[$key]) in same way as isset($str[intval($key)]), where $str and $key are strings

To handle errors best approach are exceptions:

Upvotes: 0

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