Php's question about the unpacking of unpack

pack packaging code pack ("L3", 123456789 (fixed value), strlen (message content), 1 (0 or 1)).) Message content;
the overall effect is (fixed code + content length + whether encrypted) binary conversion of these three fields as a packet header and then connect the specific message content
such as pack ("L3codes, 123456789,200,0). "i am the test"; where 200 is a character length so it is a variable value

in fact, there is no problem for client c-sharp to unpack. They intercept the header and unpack it at a fixed length. When unpacking, everything is normal

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I want to use PHP to simulate the client to receive socket messages and unpack them. When I encounter problems, I unpack them with unpack ("L3clients, $output);). Obviously, this will not work, because this result can only solve the three fields of Baotou, and the content of the message connected behind it is gone, but I don"t want to intercept the string to unpack it, which seems to be very troublesome. It seems that there is a way to solve all fields directly with unpack, including the content that does not carry out binary conversion, but I have forgotten how to write it in L3 in unpack. Unpack ("how to write here can solve the whole content directly", $output); This is feasible. What I hate is that I can"t remember how to write it.
doesn"t want to make a hard turn in any other way, so I want to take advantage of this corner, because the result is not important, I just want this usage, just use unpack to solve all the content, how to do it, which god comes to give me some advice

Php
Jul.03,2021

I remember! After testing, you can use unpack ('L3 em A return', $out); A ) to summon a normal string, alas! This is the disadvantage of not knowing the essence!

MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b34b79-2bf64.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b34b79-2bf64.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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