What is the "|=" operator in C#?

Question

In researching the cause of a bug, I came across this line of code:

Status |= (int)states.Reading;

"Status" is defined thusly:

public static int Status

...with an accessor and mutator (or "getter" and "setter"), while "states" is defined this way:

[Flags]
public  enum states

Oh yes, you're right - that is obvious here, but not in the editor (because of color syntax highlighting (the lack thereof in my VS2003 setup)). So, I'll edit the question accordingly. — B. Clay Shannon-B. Crow Raven, Jun 28 '13 at 15:46
Close, but no dupe: http://stackoverflow.com/questions/5705262/what-does-pipe-mean-in-c — Peter K., Jun 28 '13 at 15:59

Ricky Mutschlechner · Accepted Answer · 2013-06-28T16:02:02.073

10

It's the "bitwise logical OR" operator, as defined here.

x |= y is equivalent to x = x | y

Also, if you want to learn more about the "|" operator itself, you can do so here.

edited Jun 28 '13 at 16:02

answered Jun 28 '13 at 15:54

Ricky Mutschlechner

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ajaysinghdav10d · Answer 2 · 2013-06-29T08:45:43.267

While using the enumerators if you have specified [Flags] attribute on top of an "enum" member, this enables the user to select more than one enumerators in a single go. What I mean is this:-

if this is your enumerator:-

[Serializable, DataContract(Namespace = "Company.Domain.LOB.Handler")]
[Flags]
public enum BankItemStatus
{
    [EnumMember]
    UnBatched,
    [EnumMember]
    Batched,
    [EnumMember]
    Sent,
    [EnumMember]
    ReplyReceived,
    [EnumMember]
    Closed
}

Now if you use the Enum like this:-

BankItemStatus bankItemStatus = BankItemStatus.UnBatched;
BankItemStatus bankItemStatus = BankItemStatus.Sent;

The final value preserved by bankItemStatus would be BankItemStatus.Sent. You can check it like this:-

if(bankItemStatus.UnBatched==BankItemStatus.UnBatched) //FALSE
if(bankItemStatus.Sent==BankItemStatus.Sent) //TRUE

Now if you do it like this:-

BankItemStatus bankItemStatus = BankItemStatus.UnBatched;
bankItemStatus |= bankItemStatus.Sent

You will see that bankItemStatus now has both the enum members. You can check it like this:-

if(bankItemStatus.UnBatched==BankItemStatus.UnBatched) //TRUE
if(bankItemStatus.Sent==BankItemStatus.Sent) //TRUE

Hope that helps in understanding the use of |= operator in C# (in context of Enumerators).

Great answer, thanks; I once changed an answer I had marked as correct to another cat who provided a more detailed answer, and the original awarded answerer wept inconsolably, so I will leave the accepted answer as-is, although this one is great. BTW, "BatchItemStatus" should be "BankItemStatus" in the enum definition. — B. Clay Shannon-B. Crow Raven, Jun 28 '13 at 16:13

What is the "|=" operator in C#?

2 Answers2