What is the Difference Between preg_match_all and preg_match? What Are Their Appropriate Use Cases?

gitbox 2025-09-26

<span><span><span class="hljs-meta"><?php</span></span><span>
</span><span><span class="hljs-comment">// Here could be some PHP code examples that are unrelated to the article content</span></span><span>
</span><span><span class="hljs-function"><span class="hljs-keyword">function</span></span></span><span> </span><span><span class="hljs-title">helloWorld</span></span><span>(</span><span><span class="hljs-params"></span></span><span>) {
    </span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"Hello, world!"</span></span><span>;
}
</span><span><span class="hljs-title function_ invoke__">helloWorld</span></span><span>();
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<p><hr></p>
<p><p><strong>Title:</strong> What is the Difference Between preg_match_all and preg_match? What Are Their Appropriate Use Cases?</p></p>
<p><p>In PHP, regular expressions are an important tool for handling strings. The <code>preg_match

Output:

</span><span><span class="function_ invoke__">Array</span></span><span>
(
    [</span><span><span>0</span></span><span>] => apple
)

In this example, preg_match matches only the first "apple", and does not capture the subsequent ones.

2. Features of preg_match_all

Used to search for all matches of a pattern within a string.
Returns all matching results, usually in the form of an array.
Returns the number of matches; if no match is found, it returns 0.

Example:

<?php
</span><span><span>$text</span></span><span> = </span><span><span>"apple banana apple"</span></span><span>;
</span><span><span class="function_ invoke__">preg_match_all</span></span><span>(</span><span><span>'/apple/'</span></span><span>, </span><span><span>$text</span></span><span>, </span><span><span>$matches</span></span><span>);
</span><span><span class="function_ invoke__">print_r</span></span><span>(</span><span><span>$matches</span></span><span>);
?>

Output:

</span><span><span class="function_ invoke__">Array</span></span><span>
(
    [</span><span><span>0</span></span><span>] => </span><span><span class="function_ invoke__">Array</span></span><span>
        (
            [</span><span><span>0</span></span><span>] => apple
            [</span><span><span>1</span></span><span>] => apple
        )
)

As shown, preg_match_all captures both occurrences of "apple" in the string.

3. Use Cases

preg_match is suitable for:

Checking if a pattern exists in the string.
Focusing only on the first match, without needing all the matches.
Simple validations, such as checking email formats, phone numbers, etc.

preg_match_all is suitable for:

Extracting all matches of a pattern within a string.
Counting the occurrences or performing batch processing.
Complex text analysis, such as scraping all links or specific tags from a webpage.

In conclusion, preg_match is lightweight and focuses on the first match, while preg_match_all is more comprehensive, capturing all matches. Choosing the appropriate function based on the requirements can make the code more efficient and clear.