如何使用正则表达式搜索字符串是否包含列表中的至少一个单词？

Question

I have a string and need to check if any of the words in my list are in the string.
My list looks like this:

$keywords = array(
    "l.*ion",
    "test",
    'one',
    'two',
    'three'
);

1. If I have string This is my lion then I need to return true.
   
2. If I have string This is my lotion then I need to return true.
   
3. If I have string This is my dandelion then return false.
   
4. If I have string This is my location then return true.
   
5. If I have string This is my test then return true.
   
6. If I have string This is my testing then return false.
   

This is my code:

$keywords = implode($keywords,"|");
$list= "/\b$keywords\b/i";
$my_string= "This is my testing";
preg_match($list, $my_string, $matches, PREG_OFFSET_CAPTURE);
echo $matches[0][1];

But when I do This is my testing it returns a value.
What am I doing wrong? I'm expecting a numerical value if its true and and error if its false.

Answer 1

In your current regex, \bl.*ion|test|one|two|three\b, the first \b only affects the first alternative and the last \b only affects the last alternative.

Besides, since you want to only restrict matching of keywords to a single word, you cannot rely on .* pattern as . matches any char but a line break char.

You should use either \S* (to match 0+ non-whitespace chars, that also include punctuation) or \w* (to match 0+ letters, digits, and _).

So, you need to do two things: 1) redefine the $keywords array and 2) use a grouping construct around the alternatives when implodeing to group the alternatives so that the first and last \b could be applied to each alternative.

$keywords = array(
    "l\w*ion",     // <-- Here, a `\w` is used instead of .
    "test",
    'one',
    'two',
    'three'
);

$list= "/\b(?:" . implode($keywords,"|") . ")\b/i"; // <-- Here, the (?:...) groups alternatives
$my_string= "This is my testing";
if (preg_match($list, $my_string, $matches, PREG_OFFSET_CAPTURE)) {
  echo $matches[0][1];
}

See the PHP demo.

Now, the pattern is \b(?:l\w*ion|test|one|two|three)\b and \bs apply to all the alternatives. See this regex demo.