What are the common parameters of the mb_regex_set_options function? A Detailed Explanation

Common Parameter Explanation

mb_regex_set_options() accepts the following primary options, typically passed as strings:

1. i - Ignore case matching
   Example: mb_regex_set_options('i');
   Effect: Makes the regular expression case-insensitive when matching letters. For example, abc can match ABC.

2. x - Extended mode
   Example: mb_regex_set_options('x');
   Effect: Allows spaces and comments in the regular expression to improve readability. For example:

   <span><span><span class="hljs-title function_ invoke__">mb_ereg</span></span><span>(<span class="hljs-string">&#039;a # Match a
           b # Match b
           c&#039;</span>, </span><span><span class="hljs-variable">$str</span></span><span>);
   </span></span>

3. s - Single-line mode
   Example: mb_regex_set_options('s');
   Effect: Makes the dot (.) match all characters, including newline characters. By default, . does not match newline characters.

4. m - Multi-line mode
   Example: mb_regex_set_options('m');
   Effect: Makes ^ and $ match the beginning and end of each line, not just the start and end of the entire string.

5. A - Force matching from the beginning of the string
   Example: mb_regex_set_options('A');
   Effect: Requires the regular expression to start matching from the beginning of the target string. If it is not at the beginning, the match fails.

6. D - Force matching from the end of the string
   Example: mb_regex_set_options('D');
   Effect: Requires the regular expression to match from the end of the target string.

Combining Parameters

These parameters can be combined. For example, to ignore case and enable multi-line mode at the same time:

<span><span><span class="hljs-title function_ invoke__">mb_regex_set_options</span></span><span>(</span><span><span class="hljs-string">&#039;im&#039;</span></span><span>);
</span></span>

This means that the regular expression will ignore case and ^ and $ will match the start and end of each line, not just the entire string.

Usage Example

<span><span><span class="hljs-meta">&lt;?php</span></span><span>
</span><span><span class="hljs-title function_ invoke__">mb_regex_set_options</span></span><span>(</span><span><span class="hljs-string">&#039;i&#039;</span></span><span>); </span><span><span class="hljs-comment">// Ignore case</span></span><span>
<p></span>$pattern = "php";<br>
$subject = "PHP is great!";<br>
if (mb_ereg($pattern, $subject)) {<br>
echo "Match successful!";<br>
} else {<br>
echo "Match failed!";<br>
}<br>
?><br>
</span>

Output:

<span><span>Match successful!<br></span></span>

As you can see, mb_regex_set_options('i') allows php to match PHP, achieving case-insensitive matching.