在当今现代语言的抽象世界里，没有太多。File IO是一个容易想到的方法，尽管它是在已经实现的东西上执行按位操作，而不是实现使用按位操作的东西。尽管如此，作为一个简单的例子，这段代码演示了在c#中删除文件上的只读属性(这样它就可以与指定FileMode.Create的新FileStream一起使用):

//Hidden files posses some extra attibutes that make the FileStream throw an exception
//even with FileMode.Create (if exists -> overwrite) so delete it and don't worry about it!
if(File.Exists(targetName))
{
    FileAttributes attributes = File.GetAttributes(targetName);

    if ((attributes & FileAttributes.ReadOnly) == FileAttributes.ReadOnly)
        File.SetAttributes(targetName, attributes & (~FileAttributes.ReadOnly));

    File.Delete(targetName);
}

As far as custom implementations, here's a recent example: I created a "message center" for sending secure messages from one installation of our distributed application to another. Basically, it's analogous to email, complete with Inbox, Outbox, Sent, etc, but it also has guaranteed delivery with read receipts, so there are additional subfolders beyond "inbox" and "sent." What this amounted to was a requirement for me to define generically what's "in the inbox" or what's "in the sent folder". Of the sent folder, I need to know what's read and what's unread. Of what's unread, I need to know what's received and what's not received. I use this information to build a dynamic where clause which filters a local datasource and displays the appropriate information.

下面是枚举是如何组合在一起的:

    public enum MemoView :int
    {
        InboundMemos = 1,                   //     0000 0001
        InboundMemosForMyOrders = 3,        //     0000 0011
        SentMemosAll = 16,                  //     0001 0000
        SentMemosNotReceived = 48,          //     0011
        SentMemosReceivedNotRead = 80,      //     0101
        SentMemosRead = 144,                //     1001
        Outbox = 272,                       //0001 0001 0000
        OutBoxErrors = 784                  //0011 0001 0000
    }

你明白这是怎么回事了吗?通过与“收件箱”枚举值InboundMemos加上(&)，我知道InboundMemosForMyOrders在收件箱中。

下面是该方法的简化版本，它构建并返回为当前选择的文件夹定义视图的过滤器:

    private string GetFilterForView(MemoView view, DefaultableBoolean readOnly)
    {
        string filter = string.Empty;
        if((view & MemoView.InboundMemos) == MemoView.InboundMemos)
        {
            filter = "<inbox filter conditions>";

            if((view & MemoView.InboundMemosForMyOrders) == MemoView.InboundMemosForMyOrders)
            {
                filter += "<my memo filter conditions>";
            }
        }
        else if((view & MemoView.SentMemosAll) == MemoView.SentMemosAll)
        {
            //all sent items have originating system = to local
            filter = "<memos leaving current system>";

            if((view & MemoView.Outbox) == MemoView.Outbox)
            {
                ...
            }
            else
            {
                //sent sub folders
                filter += "<all sent items>";

                if((view & MemoView.SentMemosNotReceived) == MemoView.SentMemosNotReceived)
                {
                    if((view & MemoView.SentMemosReceivedNotRead) == MemoView.SentMemosReceivedNotRead)
                    {
                        filter += "<not received and not read conditions>";
                    }
                    else
                        filter += "<received and not read conditions>";
                }
            }
        }

        return filter;
    }

非常简单，但在抽象级别上是一个整洁的实现，通常不需要按位操作。

我见过它们在基于角色的访问控制系统中使用。

Bit fields (flags) They're the most efficient way of representing something whose state is defined by several "yes or no" properties. ACLs are a good example; if you have let's say 4 discrete permissions (read, write, execute, change policy), it's better to store this in 1 byte rather than waste 4. These can be mapped to enumeration types in many languages for added convenience. Communication over ports/sockets Always involves checksums, parity, stop bits, flow control algorithms, and so on, which usually depend on the logic values of individual bytes as opposed to numeric values, since the medium may only be capable of transmitting one bit at a time. Compression, Encryption Both of these are heavily dependent on bitwise algorithms. Look at the deflate algorithm for an example - everything is in bits, not bytes. Finite State Machines I'm speaking primarily of the kind embedded in some piece of hardware, although they can be found in software too. These are combinatorial in nature - they might literally be getting "compiled" down to a bunch of logic gates, so they have to be expressed as AND, OR, NOT, etc. Graphics There's hardly enough space here to get into every area where these operators are used in graphics programming. XOR (or ^) is particularly interesting here because applying the same input a second time will undo the first. Older GUIs used to rely on this for selection highlighting and other overlays, in order to eliminate the need for costly redraws. They're still useful in slow graphics protocols (i.e. remote desktop).

这些只是我最先想到的几个例子——这不是一个详尽的清单。

大约三分钟前，我刚刚使用了位异或(^)来计算与PLC串行通信的校验和…

Bitwise operators are useful for looping arrays which length is power of 2. As many people mentioned, bitwise operators are extremely useful and are used in Flags, Graphics, Networking, Encryption. Not only that, but they are extremely fast. My personal favorite use is to loop an array without conditionals. Suppose you have a zero-index based array(e.g. first element's index is 0) and you need to loop it indefinitely. By indefinitely I mean going from first element to last and returning to first. One way to implement this is:

int[] arr = new int[8];
int i = 0;
while (true) {
    print(arr[i]);
    i = i + 1;
    if (i >= arr.length) 
        i = 0;
}

这是最简单的方法，如果你想避免if语句，你可以像这样使用模方法:

int[] arr = new int[8];
int i = 0;
while (true) {
    print(arr[i]);
    i = i + 1;
    i = i % arr.length;
}

这两种方法的缺点是，模运算符是昂贵的，因为它在整数除法后寻找余数。第一个方法在每次迭代中运行if语句。然而，如果你的数组长度是2的幂，你可以很容易地生成一个像0 ..长度- 1，使用&(位和)操作符，如I & Length。知道了这些，上面的代码就变成了

int[] arr = new int[8];
int i = 0;
while (true){
    print(arr[i]);
    i = i + 1;
    i = i & (arr.length - 1);
}

下面是它的工作原理。在二进制格式中，所有2的幂减去1的数都只用1表示。例如，二进制的3是11,7是111,15是1111，等等，你懂的。现在，如果你用任意一个数对一个只由1组成的二进制数，会发生什么?假设我们这样做:

num & 7;

如果num小于或等于7，那么结果将是num，因为每个加1的&-ed就是它自己。如果num大于7，在&操作期间，计算机将考虑7的前导零，当然，在&操作后，这些前导零将保持为零，只有后面的部分将保留。比如二进制的9和7

1001 & 0111

结果将是0001，它是十进制的1，并定位数组中的第二个元素。

您可以使用它们作为一种快速而不常用的散列数据的方法。

int a = 1230123;
int b = 1234555;
int c = 5865683;
int hash = a ^ b ^ c;