Using PHP 8.1 str_starts_with() Function: Syntax, Examples, and Case Sensitivity

In PHP programming, checking whether a string starts with a specific substring is common. PHP 8.1 adds the str_starts_with() function to simplify this task.

The function takes two parameters—the haystack (main string) and the needle (substring)—and returns true if the haystack begins with the needle, otherwise false .

str_starts_with() function basic syntax:

<code>bool str_starts_with ( string $haystack , string $needle )</code>

Here $haystack is the main string and $needle is the substring to check.

str_starts_with() function examples:

<code>$mainStr = "Hello, World!";
$subStr  = "Hello";

if (str_starts_with($mainStr, $subStr)) {
    echo "主串以子串开头";
} else {
    echo "主串不以子串开头";
}
</code>

This code outputs “主串以子串开头” because “Hello, World!” starts with “Hello”.

The function can also be used to verify a URL’s protocol. Example:

<code>$url      = "https://www.example.com";
$protocol = "https";

if (str_starts_with($url, $protocol)) {
    echo "URL使用https协议";
} else {
    echo "URL不使用https协议";
}
</code>

The above prints “URL使用https协议” since the URL begins with “https”.

Note that str_starts_with() is case‑sensitive. For case‑insensitive checks, PHP provides the str_starts_with_ci() variant.

Overall, str_starts_with() offers a concise way to determine string prefixes, useful for tasks such as URL protocol validation and general substring checks.

Additional learning resources are listed, including tutorials on Vue3, Laravel, Swoole, and Workerman.