What are some common mistakes to avoid when using strpos() function in PHP?

One common mistake to avoid when using the strpos() function in PHP is not checking the return value properly. If the substring is not found, strpos() returns false, which can lead to unexpected behavior if not handled correctly. To avoid this, always use strict comparison (===) when checking the return value of strpos().

// Incorrect way - not checking the return value properly
$pos = strpos($haystack, $needle);
if ($pos) {
    // Code that assumes $needle is found
}

// Correct way - using strict comparison to check the return value
$pos = strpos($haystack, $needle);
if ($pos !== false) {
    // Code that handles the case when $needle is found
}