What is the difference between using preg_match and strpos in PHP for string matching?

When it comes to string matching in PHP, preg_match is used for pattern matching using regular expressions, while strpos is used to find the position of the first occurrence of a substring within a string. If you need to match a specific pattern or need more advanced matching capabilities, preg_match is the better choice. On the other hand, if you simply need to check if a substring exists within a string and find its position, strpos is more efficient.

// Using preg_match for pattern matching
$string = "Hello, World!";
if (preg_match("/hello/i", $string)) {
    echo "Pattern found in the string.";
} else {
    echo "Pattern not found in the string.";
}

// Using strpos for substring matching
$string = "Hello, World!";
if (strpos($string, "Hello") !== false) {
    echo "Substring found in the string.";
} else {
    echo "Substring not found in the string.";
}