It's the [comma operator](https://en.cppreference.com/w/cpp/language/operator_other#Built-in_comma_operator)
– johnDec 19 '20 at 06:26
10
It's a pointless use of the comma operator. Whoever wrote the code should be dragged outside and made to read a C++ tutorial before being allowed back in anywhere near the codebase.
– Jonathan LefflerDec 19 '20 at 06:28
3
Note that there's a comma operator in the question title too. The LHS of the operator is ignorable; it doesn't do anything useful and could be thrown away. The RHS is where the action is.
– Jonathan LefflerDec 19 '20 at 06:29
I've to admit that this looked quite surprising and confusing to me as well. (...though I know the comma operator and have used it from time to time.) ;-) Maybe, it's the fact that this is simply non-sense and hence looks that unfamiliar even although it compiles.
– Scheff's CatDec 19 '20 at 09:12