What does |= means in c++ [duplicate]

Answer 1

It's the operator for assignment by bitwise OR.

http://en.cppreference.com/w/cpp/language/operator_assignment

int result |= 5;

You cannot initialize an int and assign something to it at the same time. Initialization and assignment are different things. You'd have to write:

int result = 0;
result |= 5;

If this is what you intend, of course. Since int result |= 5; is not C++, we can only guess about your intention.

Answer 2

a |= b; is just syntactic sugar for a = a | b;. Same syntax is valid for almost every operator in C++.

But int i |= 5; is an error, because in the definition line you must have an initialisation, that is an expression that does not use the variable being declared.

int i=3;
i |= 5;

is valid and will give value 7 (3 | 5) to i.