preg_replace使用替换的文本作为变量名称

Question

I have several variables like these:

$foo = '123';  
$bar = 'bqwe';

I need to replace {$foo} and {$bar} in a string with the variables.

preg_replace('~\{\$(.*)?\}~sU', ${'\\1'}, $string);

This doesn't work.

PS: The regex might not be correct. I haven't tested it with several variables like {$asd} {$bbb}. I am testing with one variable now.

Answer 1

You should make the regex more specific. Make it match for \w+ word characters.

And then you were on the right track, but need the /e eval modifier to make the variable lookup in the local scope work:

= preg_replace('~\{\$(\w+?)\}~sUe', '${"$1"}', $string);

So when it matches foo the relacement string becomes ${"foo"} which then is used as expression. (Whereas in your original code it was incorrectly tried before the regex executed.)