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C6317

warning C6317: incorrect operator: logical-not (!) is not interchangeable with ones-complement (~)

This warning indicates that a logical-not (!) is being applied to a constant that is likely to be a bit-flag. The result of logical-not is Boolean; it is incorrect to apply the bitwise-and (&) operator to a Boolean value. Use the ones-complement (~) operator to flip flags.

Example

The following code generates this warning:

#define FLAGS   0x4004

void f(int i)
{
  if (i & !FLAGS) // warning
  { 
    // code
  }
}

To correct this warning, use the following code:

#define FLAGS   0x4004

void f(int i)
{
  if (i & ~FLAGS)
  {
    // code
  }
}

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