需要使用 preg_match_all 匹配所有相似的单词/短语

Question

我正在尝试创建一个匹配字符串中所有相似单词/短语的模式。

例如，我需要匹配：“this”、“this is”、“this is it”、“that”、“that was”、“that was not”。

它只匹配“this”的第一次出现，但它应该匹配所有次出现。

我什至尝试了锚点和单词边界，但似乎没有任何效果。

我试过（简化）：

$content = "this is it! that was not!";

preg_match_all('/(this|this is|this is it|that|that was|that was not)/i', $content, $results);

应该输出什么：

• 这个
• 这是
• 就是这样
• 那个
• 那是
• 那不是

Answer 1

鉴于您只捕获要搜索的术语，最好使用foreach 循环和substr_count 来查看每个字符串出现的次数。

例如：

$haystack = "this is it! that was not! this is not a test!";
$needles = array(
    "this",
    "this is",
    "this is it",
    "that",
    "that was",
    "that was not");

foreach ($needles as $needle) {
    // substr_count is case sensitive, so make subject and search lowercase
    $hits = substr_count(strtolower($haystack), strtolower($needle));

    echo "Search '$needle' occurs $hits time(s)" . PHP_EOL;
}

上面会输出：

Search 'this' occurs 2 time(s)
Search 'this is' occurs 2 time(s)
Search 'this is it' occurs 1 time(s)
Search 'that' occurs 1 time(s)
Search 'that was' occurs 1 time(s)
Search 'that was not' occurs 1 time(s)

如果substr_count 不能提供您需要的灵活性，那么您可以随时将其替换为preg_match_all，并使用您的个人$needle 值作为搜索词。

Answer 2

怎么样：

$content = "this is it";
preg_match_all('/(?=(this))(?=(this is))(?=(this is it))/i', $content, $results);
print_r($results);

根据cmets编辑：

$content = "this is it";
preg_match_all('/(?=(this))(?=(this is))(?=(this is it))|(?=(that))(?=(that was))(?=(that was not))/i', $content, $results);
print_r($results);

输出：

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

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

    [2] => Array
        (
            [0] => this is
            [1] => 
        )

    [3] => Array
        (
            [0] => this is it
            [1] => 
        )

    [4] => Array
        (
            [0] => 
            [1] => that
        )

    [5] => Array
        (
            [0] => 
            [1] => that was
        )

    [6] => Array
        (
            [0] => 
            [1] => that was not
        )

)

更通用：

$content = "this is it! that was not!";
preg_match_all('/\b(?=(\w+))(?=(\w+ \w+))(?=(\w+ \w+ \w+))\b/i', $content, $results);
print_r($results);

输出：

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

    [1] => Array
        (
            [0] => this
            [1] => that
        )

    [2] => Array
        (
            [0] => this is
            [1] => that was
        )

    [3] => Array
        (
            [0] => this is it
            [1] => that was not
        )

)

Answer 3

问题是 shortest 字符串选项首先出现在您的或组中：

/(this|this is|this is it)/i

PHP 将检查测试字符串是否包含(this|this is|this is it) 从左到右的项目。一旦在测试字符串中找到匹配项，它将离开组。

这会起作用，因为 PHP 将首先搜索最长的字符串：

/(this is it|this is|this)/i

Demo

Answer 4

您也可以改用以下正则表达式。

/(this(?:\sis(?:\sit)?)?)/i