You're looking at the output of a disassembler, not at the original source code. It probably reads something boring like sizeof(Identifier) in the original.

That's exactly what it is. The third parameter to memcmp is the length of the buffers to be compared - "G847MC6JZ5", the string being compared, has a length of 11 characters (including the null terminator, which is a little odd). 11 is B in hex, and is stored as an unsigned Long Long, so the representation in the disassembler is 0xBuLL.

And that string is the Blizzard identifier: https://www.virustotal.com/en/file/bdfd2017fb776b52a4604928e...

Not odd to include the null terminator if you want to ensure another string is "equal to", not just "starts with" the string you're comparing it to.

Dang it, I counted the \0 but miscounted the characters in the string.