Twos Complement On A Double

开发者_C百科How do I perform a twos complement on a double and return a double?

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If you are trying to do the two's complement of the internal bit representation of the double, you can use the BitConverter class.

Something like:

double x = 12345.6;
Int64 bits = BitConverter.DoubleToInt64Bits(x);
bits = ~bits + 1;
x = BitConverter.Int64BitsToDouble(bits);

I'm not sure why you would want to do this, though...

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You might need to cast to a long and then do the twos complement and cast back:

double x = 1245.1;
long l = (long)x;
l=~l; l++; /* complement followed by + 1 */
x = (double)l;

I didn't test this, but hopefully it gets you on the right track.

Edit: Since you cannot cast from double to long with bit representation then you might need to do something like:

double x = 1234.5;
ulong l;
unsigned char * d = (unsigned char *) &x;
l = (ulong)(*d);
l=~l; l++;
d = (unsigned char *) &l;
x = (double)(*d);

Again untested...