Understanding strrchr function

Question

I'm doing some tests with function strrchr, but I can't understand the output:

$text = 'This is my code';
echo strrchr($text, 'my');
//my code

Ok, the function returned the string before last occurrence

$text = 'This is a test to test code';
echo strrchr($text, 'test');
//t code

But in this case, why the function is returning "t code", instead "test code"?

Thanks

Answer 1

Simple! Because it finds the last occurrence of a character in a string. Not a word.

It just finds the last occurrence character and then it will echo the rest of the string from that position.

---

In your first example:

$text = 'This is my code';
echo strrchr($text, 'my');

It finds the last m and then prints the reset included m itself: my code

In your second example:

$text = 'This is a test to test code';
echo strrchr($text, 'test');

It finds the last t and like the last example prints the rest: test code

More info

Answer 2

From the PHP documentation:

needle

If needle contains more than one character, only the first is used. This behavior is different from that of strstr().

---

So your first example is the exact same as:

$text = 'This is my code';
echo strrchr($text, 'm');

RESULT

'This is my code'
         ^
        'my code'

---

Your second example is the exact same as:

$text = 'This is a test to test code';
echo strrchr($text, 't');

RESULT

'This is a test to test code'
                      ^
                     't code'

---

This function I made does what you were expecting:

/**
 * Give the last occurrence of a string and everything that follows it
 * in another string
 * @param  String $needle   String to find
 * @param  String $haystack Subject
 * @return String           String|empty string
 */
function strrchrExtend($needle, $haystack)
{
    if (preg_match('/(('.$needle.')(?:.(?!\2))*)$/', $haystack, $matches))
        return $matches[0];
    return '';
}

The regex it uses can be tested here: DEMO

example:

echo strrchrExtend('test', 'This is a test to test code');

OUTPUT:

test code