The STRRCHR () function returns a result that is sometimes incorrect

STRRCHR () function returns the result sometimes wrong?
Classic examples in the manual:
Echo strrchr ("Hello world!", "World");
Output is: world!

But continuing to try will find these wonderful results:
Echo strrchr ("Hello aaaaworld!", "Aaaaworld");
Output: aworld!

Echo strrchr ("Hello cacworld!", "Cacworld");
Output: cworld!

Echo strrchr ("abc123cache123", "cache");
Output: che123

echo strrchr ("Cache", "cache");
Output: Che

And so on, in short, will return incomplete, always missing the first few characters, do not know why??
------Solution--------------------

A second parameter:
1. If more than one character is included, use only "first character"
2. If it is not a string, it will be converted to an integer and treated as a character order value
Example: Echo strrchr ("Hello aaaaworld!", "Aaaaworld");
Find string only with a, output: aworld!
This is right.


------Solution--------------------
PHP Manual:
If needle contains more than one character, only the first is used
If needle contains more than one character, only the first character is used. This behavior differs from STRSTR ().

W3school:
Specifies the character to find. If the parameter is a number, the character that matches the ASCII value of the number is searched.

Obviously the latter ignores the description "use only the first character"
But the characters to look for and the string to find are different.

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