What's the most efficient test of whether a PHP string ends with another string?

Question

The standard PHP way to test whether a string $str ends with a substring $test is:

$endsWith = substr( $str, -strlen( $test ) ) ==          


        

Answer 1

$endsWith = substr_compare( $str, $test, -strlen( $test ) ) === 0

Negative offset "starts counting from the end of the string".

Answer 2

It depends on which sort of efficiency you care about.

Your version uses more memory due to the extra copy from the use of substr.

An alternative version might search the original string for the last occurrence of the substring without making a copy, but would probably be slower due to more testing.

Probably the most efficient way is to do loop char-by-char from the -sterlen(test) position till the end of the string and compare. That's the minimal amount of comparisons you can hope to do and there's hardly any extra memory used.

Answer 3

This method is a tiny bit more memory-expensive, but it is faster:

stripos(strrev($haystack), $reversed_needle) === 0;

This is best when you know exactly what the needle is, so you can hard-code it reversed. If you reverse the needle programatically, it becomes slower than the earlier method.

Answer 4

Another way would be to use the strrpos function:

strrpos($str, $test) == strlen($str) - strlen($test)

But that’s not faster.

Answer 5

for single-char needle:

if (@strrev($haystack)[0] == $needle) {
   // yes, it ends...
}

Answer 6

This is pure PHP, without calling external functions, except for strlen.

function endsWith ($ends, $string)
{
    $strLength = strlen ($string);
    $endsLength = strlen ($ends);
    for ($i = 0; $i < $endsLength; $i++)
    {
        if ($string [$strLength - $i - 1] !== $ends [$i])
            return false;
    }
    return true;
}