Trying to store interface when preg_match_all is executed using php

I would like to store the interface name only. So in this case, I would like to store Interface900. Below is my code. Can’t seem to figure out how to do this.

$str = '[TIMETRA-VRTR-MIB::vRtrIfName.22.178] => STRING: "interface900" ';

preg_match_all("!^STRING: "?(.*?)"?$!", $str, $matches)) 
print_r($matches);

Also tried

preg_match_all('(STRING: ")([w-_]*)', $str, $matches);
print_r($matches);

IN both cases, it’s not printing Interface900. I’m not too good with regex or php. Can someone help me please?

Answer

Your RegEx is incorrect, it should be:

STRING: "?(.*?)"? $
STRING: "?              // Match the string 'STRING: ' followed by an optional double quote
           (.*?)         // Non-greedy capture anything until the next character in the pattern
                "? $    // Match an optional double quote followed by a space and the end of the string {$}

Example

preg_match_all("/STRING: "?(.*?)"? $/", $str, $matches);
print_r($matches);

/* Output:
    Array
    (
        [0] => Array
            (
                [0] => STRING: "interface900" 
            )
    
        [1] => Array
            (
                [0] => interface900
            )
    
    )
*/

preg_match("/STRING: "?(.*?)"? $/", $str, $matches);
print_r($matches);

/* Output:
    Array
    (
        [0] => STRING: "interface900" 
        [1] => interface900
    )
*/

Why your RegEx failed

^STRING: "?(.*?)"?$
^                        // Matches the start of the string {DOESN'T MATCH}
 STRING: "?             // Match the string 'STRING: ' followed by an optional double quote
            (.*?)        // Non-greedy capture anything until the next character in the pattern
                 "?$    // Match an optional double quote followed immediately by the end of the string {DOESN'T MATCH}