How to concatenate PHP variable name?

Question

I have a PHP for loop:

for ($counter=0,$counter<=67,$counter++){

echo $counter;
$check="some value";

}

What I am trying to achieve is use the for loop variable and append it to the name of another variable.

Bascially, I want the PHP output to be as follows for each row

1
$check1="some value"

2
$check2="some value"

3
$check3="some value"

4
$check4="some value"

etc etc

I have tried $check.$counter="some value" but this fails.

How can I achieve this? Am I missing something obvious?

Would the use of an array be preferable to this method? $myVar = array(); for($i = 0; $i <= 67; $i++) { $myVar[] = "Some Value"; } — Matt
– Matt, Commented Jul 31, 2012 at 12:40

score 76 · Accepted Answer · 2017-09-26 12:46:04Z

76

The proper syntax for variable variables is:

${"check" . $counter} = "some value";

However, I highly discourage this. What you're trying to accomplish can most likely be solved more elegantly by using arrays. Example usage:

// Setting values
$check = array();
for ($counter = 0; $counter <= 67; $counter++){
    echo $counter;
    $check[] = "some value";
}

// Iterating through the values
foreach($check as $value) {
    echo $value;
}

edited Sep 26, 2017 at 12:46

answered Jul 31, 2012 at 12:39

user142162

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4 Comments

Smudger Over a year ago

Thanks Tim, is there a situaton when this is acceptable or is it functionality no longer used?

user142162 Over a year ago

@Smudger: Off the top of my head, I can't think of a solid case where one would use variable variables. Looking at the comments on the documentation page might give you some ideas on where they could be useful. Just keep in mind that what you read there may not be considered best practice.

Nosajimiki Over a year ago

Concatenation is never the "cleaner" solution, but there may be cases where you have old, highly developed code that was never intended to correlate A+B where it is simply much easier to do this than rewriting hundreds of lines of code just to replace old variable types with arrays

Nosajimiki Over a year ago

The one case I can think of where I use them is with HTML forms where I have recursively built inputs. When you Post it, it will post as a bunch of variables and not as an array; so, recursively calling them may be easier with $_POST[${"myInputName".$i}]

arma · Accepted Answer · 2013-07-09 18:39:16Z

7

This is usable in some cases. For example if your app has something like 2 language entries in DB.

echo $this->{'article_title_'.$language};

That's much more usable than for example this;

if($language == 'mylanguage1')
    echo $this->article_title_mylanguage1;
else
    echo $this->article_title_mylanguage2;

Obviously this is what you should not have to do in your multilingual app, but i have seen cases like this.

answered Jul 9, 2013 at 18:39

arma

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1 Comment

Pathros Over a year ago

Yeah, it is my case: I got 3 columns entries in DB. So i need to loop like that from a checkboxes group

Adunahay · Accepted Answer · 2012-07-31 12:43:53Z

6

You should use ${'varname'} syntax:

for ($counter=0,$counter<=67,$counter++){
    echo $counter;
    ${'check' . $counter} ="some value";
}

this will work, but why not just use an array?

$check[$counter] = "some value";

answered Jul 31, 2012 at 12:43

Adunahay

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Comments

Matt · Accepted Answer · 2012-07-31 12:42:28Z

0

An array would accomplish this.

$check = array();

for($counter = 0; $counter <= 67; $counter++) {
    $check[] = "some value";
    var_dump($check[$counter]);
}

answered Jul 31, 2012 at 12:42

Matt

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