Question

在下面的代码中为什么PHP preg_match返回false？注意：我读过一些与我的问题标题相同的旧问题，但背景不同

<html>
    <head>
    </head>
    <body>
        <?php
        $str = "This is a test for PCRE.";
        $ptrn = "This";
        $preg_match_result_arr;
        $preg_match_result = preg_match($ptrn, $str, $preg_match_result_arr);

        if (1 === $preg_match_result)
        {
            echo "The pattern has matched in the string:<br/>".
                "the match is $preg_match_result_arr[0]<br/>";
        }   
        elseif (0 === $preg_match_result) 
        {
            echo "The pattern has not matched in the string:<br/>";
        }
        elseif (false === $preg_match_result)
        {
            echo "An error has occured in matching<br/>";
        }

        ?>
    </body>
</html>

Answer 1

你错过了分隔符，你的模式应该是这样的（#使用但是它可能是其他东西）：

$ptrn = "#This#";

Answer 2

你的表达方式不正确，它应该被这样的分隔符所包围。

$ptrn = '/This/';

Answer 3

将您的模式放在'/ pattern /'

中

例如：

$ptrn='/^This/'

Answer 4

您可以考虑使用 CleanRegex，这会为您抛出异常，并自动定界符您的模式：

<?php
    try {
        pattern("This")
            ->match("This is a test for PCRE.")
            ->first(function (Match $match) {
                echo "The pattern has matched in the string:<br/>".
                     "the match is $match<br/>";
            });
    }
    catch (MatchPatternException $e)
    {
        echo "An error has occured in matching<br/>";
    }

或者您可以

if (pattern("This")->matches("This is a test for PCRE.")) {
    echo "The pattern has matched in the string:<br/>";
}
else {
    echo "The pattern has not matched in the string:<br/>";
}

PHP preg_match返回false

4 个答案: