$array = array(':('=>"sad",'-_-'=>"bow",'bla'=>"blabla");
$input = "I love ***! :bow: so much";
$output = str_replace(array_keys($array), array_values($array), $input);

抱歉..没看清楚.

尝试 2:

preg_replace('`:(\w+):`', '<img src="smily/\1.gif" alt=""/>', $input);

反正就是这样.

可能必须使用 $1 代替 \1.阅读文档.

Might have to use $1 in place of \1. Read the docs.