Stripos Search failed and returns false. How to handle it elegantly?

M66 2025-05-13

In PHP, stripos() is a very common function to find the first occurrence of a string in another string, insensitively. If found, stripos() returns an integer indicating the starting position of the matching string in the target string; if not found, false is returned.

Here comes the problem: since the return is " 0 or false ", it is easy to make errors in the conditional judgment.

Let me give you a common pitfall:

 if (stripos($haystack, $needle)) {
    echo "Found！";
} else {
    echo "Not found！";
}

If $needle is at the beginning of $haystack (position 0), stripos() returns 0 , and if (0) will be treated as false, resulting in "not found" output, logical error!

The correct way to judge

To gracefully handle the situation where stripos() returns false , we should clearly determine whether it is false , rather than a simple Boolean judgment:

 $pos = stripos($haystack, $needle);
if ($pos !== false) {
    echo "Found，In location：$pos";
} else {
    echo "Not found！";
}

By using the congruent comparison symbol !== , we can accurately distinguish 0 and false .

A further package: Write a gadget function

To make the code clearer and reusable, we can encapsulate a helper function:

 function containsIgnoreCase($haystack, $needle) {
    return stripos($haystack, $needle) !== false;
}

// Example of usage
if (containsIgnoreCase("https://m66.net/news", "NEWS")) {
    echo "Include keywords！";
} else {
    echo "不Include keywords！";
}

This way, writing code is easy to read and reduces repetitive logic, making it very suitable for widespread use in projects.

Practical application: determine whether the user's access source contains certain keywords

Suppose we need to determine whether the URL the user access contains utm_source :

stripos