Can someone explain what is the operator &= for?
I searched, but I got only results with & or =.
a &= b;
Is the same as
a = a & b;
& is the "bitwise and operator", search for that.
It's a shorthand operator which allows you to collapse
a = a & b
into
a &= b
Apart from bitwise operations on integers, &= can be used on boolean values as well, allowing you to collapse
a = a && b
into
a &= b
However, in the case of logical operation, the expanded form is short-circuiting, while the latter collapsed form does not short-circuit.
Example:
let b() be a function that returns a value and also does stuff that affects the program's state
let a be a boolean that is false
if you do
a = a && b()
the short-circuit happens: since a is false there's no need to evaluate b (and the extra computation that might happen inside b() is skipped).
On the other hand, if you do
a &= b()
the short-circuit doesn't happen: b is evaluated in any case, even when a is false (and evaluating b() wouldn't change the logical outcome), thus any extra computation that might happen inside b() does get executed.
This
x &= y;
is equivalent to
x = x & y;
Note that & is the bitwise and operator.
If i remember correctly it biwise operation...for example it can be used with [Flags]Enum. It check if your flag variable has specific value.
In C#(and in most languages I think) its the bitwise assigment operator.
a &= b is equivalent of a = a & b
a &= b is equivalent to a = a & b
来源：https://stackoverflow.com/questions/8910623/what-is-this-operator