简答

您想对当前值的位与操作用的Bitwise不你想取消设置在标志的操作。按位非反转每个比特（即0 => 1，1 => 0）。

标志=标志和放大器; 〜MASK; 或标记和放大器; =〜MASK;

长的答案

  ENABLE_WALK = 0 // 00000000
ENABLE_RUN = 1 // 00000001
ENABLE_SHOOT = 2 // 00000010
ENABLE_SHOOTRUN = 3 // 00000011值= ENABLE_RUN // 00000001
值| = ENABLE_SHOOT // 00000011或相同ENABLE_SHOOTRUN
 

当您执行的位与价值的按位不是你想要取消设置。

 值=价值和放大器; 〜ENABLE_SHOOT // 00000001
 

你实际上是这样做的：

  0 0 0 0 0 0 1 1（当前值）
   ＆安培; 1 1 1 1 1 1 0 1（〜ENABLE_SHOOT）
      ---------------
      0 0 0 0 0 0 0 1（结果）
 

There is a variable that holds some flags and I want to remove one of them. But I don't know how to remove it.

Here is how I set the flag.

my.emask |= ENABLE_SHOOT;

Short Answer

You want to do an Bitwise AND operation on the current value with a Bitwise NOT operation of the flag you want to unset. A Bitwise NOT inverts every bit (i.e. 0 => 1, 1 => 0).

flags = flags & ~MASK; or flags &= ~MASK;.

Long Answer

ENABLE_WALK  = 0    // 00000000
ENABLE_RUN   = 1    // 00000001
ENABLE_SHOOT = 2    // 00000010
ENABLE_SHOOTRUN = 3 // 00000011

value  = ENABLE_RUN     // 00000001
value |= ENABLE_SHOOT   // 00000011 or same as ENABLE_SHOOTRUN

When you perform a Bitwise AND with Bitwise NOT of the value you want unset.

value = value & ~ENABLE_SHOOT // 00000001

you are actually doing:

      0 0 0 0 0 0 1 1     (current value)
   &  1 1 1 1 1 1 0 1     (~ENABLE_SHOOT)
      ---------------
      0 0 0 0 0 0 0 1     (result)