匹配正则表达式没有一个单词背后的另一个单词

Question

I have to match the word 'like' without the word 'not' before it. In the example below, there is a 'not' before the word 'like' so it shouldn't have matched it. How would I fix this?

$tempInput = "i do not like to fail";
if (preg_match("~(?!not )(like)~", $tempInput, $match)) {

print_r($match);

}

Result:

Array ( [0] => like [1] => like )

Need Result:

Null

Answer 1

A negative lookbehind for literal string not like this will do.

Regex: /(?<!not )like/

Explanation:

• (?<!not ) will look behind and check if there is word not.

• like if it is not present then like will be matched.

Regex101 Demo