php - stripos returns false when special characters is used

Question

I am using the stripos function to check if a string is located inside another string, ignoring any cases.

Here is the problem:

stripos("?", "?")

returns false. While

stripos("?", "?")

returns true.

As you might see, it looks like the function does NOT do a case-insensitive search in this case.

The function has the same problems with characters like ?? and ??. These are Danish characters.

Answer 1

Use mb_stripos() instead. It's character set aware and will handle multi-byte character sets. stripos() is a holdover from the good old days when there was only ASCII and all chars were only 1 byte.