Setting a bit (设置一点)
Use the bitwise OR operator ( | ) to set a bit. (使用按位或运算符（ | ）进行设置。)
number |= 1UL << n;
That will set the n th bit of number . (这将设置number第n位。) n should be zero, if you want to set the 1 st bit and so on upto n-1 , if you want to set the n th bit. (n应该是零，如果你想设置1 ST位，依此类推高达n-1如果你想设置的n个位。)
Use 1ULL if number is wider than unsigned long ; (如果number大于unsigned long则使用1ULL ;) promotion of 1UL << n doesn't happen until after evaluating 1UL << n where it's undefined behaviour to shift by more than the width of a long . (直到对1UL << n进行评估后，才发生1UL << n提升，在这种情况下，未定义的行为是将偏移的长度大于long的宽度。) The same applies to all the rest of the examples. (其他所有示例也是如此。)
Clearing a bit (清除一点)
Use the bitwise AND operator ( & ) to clear a bit. (使用按位AND运算符（ & ）清除一位。)
number &= ~(1UL << n);
That will clear the n th bit of number . (这将清除n个位number 。) You must invert the bit string with the bitwise NOT operator ( ~ ), then AND it. (您必须使用按位NOT运算符（ ~ ）反转位字符串，然后将其取反。)
Toggling a bit (切换一点)
The XOR operator ( ^ ) can be used to toggle a bit. (XOR运算符（ ^ ）可用于切换一位。)
number ^= 1UL << n;
That will toggle the n th bit of number . (这将切换n的个位number 。)
Checking a bit (检查一下)
You didn't ask for this, but I might as well add it. (您没有要求这样做，但我也可以添加它。)
To check a bit, shift the number n to the right, then bitwise AND it: (要检查一点，请将数字n右移，然后按位与它相乘：)
bit = (number >> n) & 1U;
That will put the value of the n th bit of number into the variable bit . (这将把数字的第n位的number放入可变bit 。)
Changing the n th bit to x (将第n位更改为x)
Setting the n th bit to either 1 or 0 can be achieved with the following on a 2's complement C++ implementation: (在2的补码C ++实现中，可以通过以下操作将第n位设置为1或0 ：)
number ^= (-x ^ number) & (1UL << n);
Bit n will be set if x is 1 , and cleared if x is 0 . (如果x为1 ，则将设置n位；如果x为0 ，则将其清除。) If x has some other value, you get garbage. (如果x具有其他值，则会产生垃圾。) x = !!x will booleanize it to 0 or 1. (x = !!x会将其布尔值设为0或1。)
To make this independent of 2's complement negation behaviour (where -1 has all bits set, unlike on a 1's complement or sign/magnitude C++ implementation), use unsigned negation. (为了使它独立于2的补码取反行为（其中-1设置了所有位，与1的补码或符号/幅度C ++实现不同），请使用无符号取反。)
number ^= (-(unsigned long)x ^ number) & (1UL << n);
or (要么)
unsigned long newbit = !!x; // Also booleanize to force 0 or 1
number ^= (-newbit ^ number) & (1UL << n);
It's generally a good idea to use unsigned types for portable bit manipulation. (使用无符号类型进行可移植位操作通常是一个好主意。)
or (要么)
number = (number & ~(1UL << n)) | (x << n);
(number & ~(1UL << n)) will clear the n th bit and (x << n) will set the n th bit to x . ((number & ~(1UL << n))将清除第n位，而(x << n)将第n位设置为x 。)
It's also generally a good idea to not to copy/paste code in general and so many people use preprocessor macros (like the community wiki answer further down ) or some sort of encapsulation. (通常不要复制/粘贴代码也是一个好主意，因此许多人使用预处理器宏（例如社区Wiki进一步回答 ）或某种封装形式。)
