Mixing a PHP Variable With a String Literal

Mixing a PHP variable with a string literal

echo "{$test}y";

You can use braces to remove ambiguity when interpolating variables directly in strings.

Also, this doesn't work with single quotes. So:

echo '{$test}y';

will output

{$test}y

PHP variables in HTML string

If you want to add vars into variable without concat then maybe you are looking for something like this

$information = "Info";
$msg = "<html><body>
 <p>Bla-bla-bla $information</p></body></html>";

use your double quotes
Be aware if your var $information is array like this:

$information['info'] = "Info";
$information['id_info'] = 1;
$msg = "<html><body>
 <p>Bla-bla-bla $information[info]</p>
 <a href\"somepage.php?id=$information[id_info]\">Link</a></body></html>";

Double and single quotes

$email = 'someone@example.com';
$var = 'My email is $email'; // My email is $email
$var = "My email is $email"; // My email is someone@example.com

isset using mixed variable with string literal

you have to use variable variables. use

<?php
$label_test = "Hello";
$value = "test";
echo (isset(${"label_{$value}"})) ? "label_{$value}" : $label;
?>

PHP - concatenate or directly insert variables in string

Between those two syntaxes, you should really choose the one you prefer :-)

Personally, I would go with your second solution in such a case (Variable interpolation), which I find easier to both write and read.

The result will be the same; and even if there are performance implications, those won't matter¹.

As a sidenote, so my answer is a bit more complete: the day you'll want to do something like this:

echo "Welcome $names!";

PHP will interpret your code as if you were trying to use the $names variable -- which doesn't exist.
- note that it will only work if you use "" not '' for your string.

That day, you'll need to use {}:

echo "Welcome {$name}s!"

No need to fallback to concatenations.

Also note that your first syntax:

echo "Welcome ".$name."!";

Could probably be optimized, avoiding concatenations, using:

echo "Welcome ", $name, "!";

(But, as I said earlier, this doesn't matter much...)

_{1 - Unless you are doing hundreds of thousands of concatenations vs interpolations -- and it's probably not quite the case.}

PHP string to contain and output another PHP variable

You cannot store strings with PHP interpolation symbols. Double-quoted strings are interpolated at runtime.

I'd say you have three options...

Store the various parts in your database and construct them in your query. For example (assuming MySQL)
```
SELECT
  CONCAT(VideoProviders.embed_prefix, Article.video_url) AS embedcode,
  -- etc
```
with VideoProviders.embed_prefix containing 'https://www.youtube.com/embed/', 'https://player.vimeo.com/video/', etc
Store the URL with placeholders for the video id and (again assuming MySQL) use the REPLACE function. For example
```
VideoProviders.embedcode = 'https://www.youtube.com/embed/{VIDEO_ID}'
```
and
```
SELECT
  REPLACE(VideoProviders.embedcode, '{VIDEO_ID}', Article.video_url) AS embedcode,
  -- etc
```
This would be the preferred solution if the video id doesn't always appear at the end of the URL.
Store a printf style pattern in embedcode, eg 'https://www.youtube.com/embed/%s' and put it together with PHP, eg
```
$embedcode = sprintf($row['embedcode'], $row['video_url');
```

Made a php variable and now can't run it

Try:

$questionID = $quizinfo['Q' . $ques_num . '_ID'];

It should work.

When you write:

$questionID = '$quizinfo[\'Q' . $ques_num . '_ID\']';

$quizinfo[…] is not interpreted. It is taken as a string.

See also:

Php variables inside strings
PHP - concatenate or directly insert variables in string
PHP: variables in strings without concatenation
PHP: Beware of Variables Inside Strings
Mixing PHP variable with string literal

Unterminated string literal - passing php variable to javascript function, from onclick handler, in echo block

Encode PHP variables as JSON before outputting in order to turn them into valid JavaScript literals.

e.g.

var s = <?php echo json_encode($val); ?>

Mixing a PHP Variable With a String Literal