PHP正则表达式在字符之间或字符串结尾之间进行选择

Question

I have been working on this problem for several days and it's starting to drive me crazy. I'm comfortable using regular expressions but this one thing seems to be escaping me.
I need to match a string between a set of characters if they exist otherwise it should match to the end of the line.

For example: I'm just trying to get "content" out of the following example:

$str1="title:content @description"
$str2="title:content"
preg_match("/:(.*?)[(@)|(:)|(\*)]?$/",$str1,$content);
preg_match("/:(.*?)[(@)|(:)|(\*)]?$/",$str2,$content);

$str1 outputs:"content @description"

$str2 outputs:"content"

note: the strings may be in a different order or may not have a special character (@,:,or *) in it or they might have one so there's no "end of string" character that will be common besides "end of line".

I've tried every combination i can think of to make the entire "or" statement conditional and read a ton of posts with similar but not quite the same question.

Answer 1

You can write:

preg_match("/:(.*?)(?:[@:*]|$)/", $str1, $content);

(note that the match ends at one of @:* or end-of-string, using | ; your version has the [@:*] optional, but makes the end-of-string mandatory.)

or simply:

preg_match("/:([^@:*]*)/", $str1, $content);

(meaning "a colon, followed by zero or more characters that aren't in @:* ").