PHP eval() function

nxny · 01-08-2003, 01:49 PM

<?php
$test = 'success';

//Case 1. simple variable
$string = 'This is a $test';

// Case 2. Indexed Array variable
$string = 'This is a $_SERVER["SERVER_NAME"]';

echo $string . "<br>";
eval("\$string = \"$string\";");
echo $string . "<br>";
?>

Case 1. Works fine.
Case 2. Errors out at the eval() function. Yes, I've tried escaping the quotes, doubling them and what not!!

I dont want to use string concatenation to make this work.

leed_25 · 01-09-2003, 01:12 PM

It seems to work like this:

Code:

<?php
$test = 'success';

//Case 1. simple variable
$string = 'This is a $test';

// Case 2. Indexed Array variable
$string = 'This is a {$_SERVER["SERVER_NAME"]} ';

echo $string . "<br>";
eval("\$string = \"$string\";");
echo $string . "<br>";
?>

here's a little snippet from the php site which
explains how to do variable substitution in quoted
strings:

,----[ http://www.php.net/manual/en/language.types.string.php ]
| Complex (curly) syntax
|
| This isn't called complex because the syntax is
| complex, but because you can include complex
| expressions this way.
|
| In fact, you can include any value that is in the
| namespace in strings with this syntax. You simply
| write the expression the same way as you would outside
| the string, and then include it in { and }. Since you
| can't escape '{', this syntax will only be recognised
| when the $ is immediately following the {. (Use "{\$"
| or "\{$" to get a literal "{$"). Some examples to make
| it clear:
`----

I hope this helps.

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nxny · 01-09-2003, 02:39 PM

Geez, that is EXACTLY what I was looking for. Kicks butt!!

Thanks a ton, leed25. I was about to conclude that the PHP parser wont be able to handle such a construct.