PHP Variable used in a variable

Question

I'm new to PHP so please forgive me if this is a stupid question.

How do you include a variable in a variable?

What I mean is:

<?php

   $variable_a = 'Adam';
   $variable_b = '$variable_a';

?>

In other words the second variable is the same as the first one.

I won't bother explaining why I need to do it (it will confuse you!), but I just want to know firstly if it's possible, and secondly how to do it, because I know that code there doesn't work.

Cheers,

Adam.

Better to write without quotes, but if you want to use quotes then use double quotes instead of single. — Narek, Feb 01 '12 at 10:17
http://stackoverflow.com/questions/3446216/difference-between-single-quote-and-double-quote-string-in-php — Narek, Feb 01 '12 at 10:18
dont forget: [PHP variables](http://www.php.net/manual/en/language.variables.basics.php) — Jorge Pinho, Feb 01 '12 at 10:20
Read the reference variable and the variables in single in double quotes. it will remove your confusion. — Code Lღver, Feb 01 '12 at 10:24

score 4 · Answer 1 · answered Feb 01 '12 at 10:16

4

Don't use the quotes, they indicate a string. Just point to the variable directly, like this:

$variable_b = $variable_a;

answered Feb 01 '12 at 10:16

Oldskool

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Ahhhh! So you don't include the quotes. No wonder it was outputting as text. Thanks mate perfect! – Adam McArthur Feb 01 '12 at 10:18

score 2 · Accepted Answer · answered Feb 01 '12 at 10:18

If you want the variables to be equal, use:

$variable_b = $variable_a;

If you want the second variable to contain the first, use variable parsing:

$variable_b = "my other variable is: $variable_a";

Or concatenation:

$variable_b = 'my other variable is: ' . $variable_a;

score 2 · Answer 3 · answered Feb 01 '12 at 10:47

PHP have this advantage in producing one string variable's value based on another. To do this, write code like this:

$b = "My name is $name.";

The following code does NOT work:

$b = '$name';

Other occasions in which coding like this works are:

$b = <<<STRING
    Hello, my name is $name...
STRING;

If you want to access an array, use:

$b = "My ID is {$id['John Smith']}.";

and of course,

$b = <<<STRING
    Hello, my name is {$username}, my ID is {$id['John Smith']}.
STRING;

I recommend using {} because I frequently use Chinese charset in which occasion coding like

$b = "我是$age了。";

will cause PHP look up for variable $age了。 and cause error.

Stefan Konno · Answer 4 · 2012-02-01T10:24:41.373

1

Either without quotes to reference the variable directly, since quotations means it's a string

$variable_b = $variable_a;

Or you can ommit the variable in double quotations, if you want it to appear in a string.

$variable_b = "My name is $variable_a";

edited Feb 01 '12 at 10:24

answered Feb 01 '12 at 10:17

Stefan Konno

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PHP Variable used in a variable

4 Answers4