Why have an empty PHP Variable?

Question

I've been reviewing a lot of PHP code lately and I keep coming across situations like this:

function () {

    $var = '';

    if ( ... ) {
      $var = '1';
    }

    echo $var;

}

An empty variable is declared and then later defined.

Is there a reason behind this?

The only reason I can think of for doing this is just to make sure $var starts out as empty in case it's previously defined.

It's a preset in this very case, because the second assignment is conditional. $var would else resolve to NULL; with a Notice (which this approach is often used for to eschew). — mario
– mario, Commented Aug 31, 2014 at 2:24
Try to put "@" before the variable at echo. echo @$var; this will by pass the E_NOTICE — sugunan
– sugunan, Commented Sep 6, 2014 at 15:45

Sebas · Accepted Answer · 2014-08-31 02:25:39Z

5

If you don´t define $var and the if condition fails, you get an undefined variable $var, assumed constant var notice. (E_NOTICE)

edited Aug 31, 2014 at 2:25

answered Aug 31, 2014 at 2:24

Sebas

21.6k9 gold badges60 silver badges109 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Havenard Over a year ago

Not exactly an Error, just a Notice. Still should be avoided. Besides, attempting to obtain the value of an undefined variable will get you null, not an empty string. This can be relevant depending on what you are doing.

John Conde · Accepted Answer · 2014-08-31 02:24:05Z

2

If if ( ... ) { evaluates to false $var will never be defined. So when echo $var is executed a NOTICE will be displayed that $var is not defined. By defining a default value you prevent this situation from occurring.

answered Aug 31, 2014 at 2:24

John Conde

220k100 gold badges464 silver badges504 bronze badges

Comments

Chemdream · Accepted Answer · 2014-08-31 02:30:25Z

0

If you did not have the $var = ''; you would then need

if (isset($var)) {
    echo $var;
} else {
    echo '';
}

This really helps when you are returning something like an AJAX call. You can initialize everything to '' or FALSE. This way, javascript won't error because something it is expecting is always there, even if it is FALSE or blank.

answered Aug 31, 2014 at 2:30

Chemdream

6272 gold badges10 silver badges30 bronze badges

Collectives™ on Stack Overflow

Why have an empty PHP Variable?

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related