How to make variables work in Single Quotes properly?

Question

I want those variables to be filled with their values, but in config.php file its writing the variable name itself, I want like $host convert to 'localhost' with single quotes in the config.php file.

    $handle = fopen('../config.php', 'w');
    fwrite($handle, '
    <?php
    $connection = mysql_connect({$host}, {$user}, {$pass});
    ?>
    ');
    fclose($handle);

You are using [an **obsolete** database API](http://stackoverflow.com/q/12859942/19068) and should use a [modern replacement](http://php.net/manual/en/mysqlinfo.api.choosing.php). — Quentin, Jul 19 '14 at 15:04
Its just a project for my institute, I didn't learn mysqli or pdo yet. — harsimarriar96, Jul 19 '14 at 15:11

score 4 · Answer 1 · answered Jul 19 '14 at 15:01

4

You can't. Single quotes do not interpolate variables. It the major thing that distinguishes them from double quotes. Use double quotes (or something else, such as sprintf) instead.

answered Jul 19 '14 at 15:01

Quentin

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I want to write the config.php file can you help me how can I write it? with the variables printing. – harsimarriar96 Jul 19 '14 at 15:04
@harsimarriar96 Quentin has answered you're question, you're on the right lines so go and have a go at doing it yourself. If you have any further questions: create a new question. – David Barker Jul 19 '14 at 15:11

Kyle Emmanuel · Accepted Answer · 2014-07-19T15:29:10.210

2

If you use variables within single quotes, they will be represented as strings instead of variables.

You can also do it like this:

// Get from $_SESSION (if started)
$host = $_SESSION['host'];
$user = $_SESSION['user'];
$pass = $_SESSION['pass'];

$handle = fopen('../config.php', 'w');

// try with the {}
$content = '<?php $connection = mysql_connect('."{$host},"."{$user},"."{$pass});".'?>';

// or you can try this too, but comment out the other one:
$content = '<?php $connection = mysql_connect('."\"$host\","."\"$user\","."\"$pass\");".'?>';

fwrite($handle, $content);
fclose($handle);

edited Jul 19 '14 at 15:29

answered Jul 19 '14 at 15:06

Kyle Emmanuel

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1
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It is not showing the values of $host, $user, $pass. Its giving me mysql_connect(,,); and the rest of code works fine. – harsimarriar96 Jul 19 '14 at 15:09
Have you defined the values of $host, $user, and $pass? Maybe they are empty variables. @harsimarriar96 – Kyle Emmanuel Jul 19 '14 at 15:11
There are some values which I get from session. – harsimarriar96 Jul 19 '14 at 15:14
try to print the $_SESSION variable using `print_r()` and find the indexes used for the values of 'host', 'user', and 'pass'. – Kyle Emmanuel Jul 19 '14 at 15:18
This worked, I was missing session_start(); But there is still a problem, The values in config.php are not in '' single quotes. – harsimarriar96 Jul 19 '14 at 15:27
You can add double-quotation marks using the backslash + mark: `\"` – Kyle Emmanuel Jul 19 '14 at 15:30

score 1 · Answer 3 · answered Jul 19 '14 at 15:06

1

If you use double quotes it works:

$handle = fopen('../config.php', 'w');
fwrite($handle, "
<?php
$connection = mysql_connect({$host}, {$user}, {$pass});
?>
");
fclose($handle);

answered Jul 19 '14 at 15:06

datagutten

163
1
9

When I try to double quotes, It reads the $connection variable too, I want it to read only $host, $user, $pass and the rest should be written as it is. – harsimarriar96 Jul 19 '14 at 15:10
Put a \ in front of $connection to escape it to avoid php reading it as a variable. – datagutten Jul 19 '14 at 15:17

How to make variables work in Single Quotes properly?

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