php get the string after the last punctuation and the string before the punctuation

1. In the development process, the required string needs to be processed, specifically to obtain the character 191 of the string 'm-184-191', the code is as follows

$ spm = 'm-184-191';
$result = substr($spm,strripos($spm,"-")+1);
echo $result;

 

2. In the development process, the required strings need to be processed, specifically to obtain the character 'admin/auth' of the string 'admin/auth/index', the code is as follows

$url = 'admin/auth/index';
$result = substr($url,0,strrpos($url,"/");
echo $result;

The above two pieces of code mainly use several functions: ① strrpos() function finds the last occurrence of a string in another string (case-sensitive);

　　　　　　　　　　　　　　　  ② strripos - finds the position of the last occurrence of a string in another string (case-insensitive);

　　　　　　　　　　　　　　　  ③ The substr() function returns part of the string.

The first piece of code to understand: find the last occurrence of '-' in the last string 'm-184-191' through strripos, then add one, and then intercept the string after the last '-' through substr (excluding the last A '-')
Understanding of the second piece of code: find the last occurrence of '/' through strrpos, and intercept the string from the beginning of the string 'admin/auth/index' to the position before the last '/' through string interception ( excluding the final '/')