Bit transposing

[silverwatch]

Hello,
i was wondering on how to do a bit transposition.
I really need this for a project i am doing encrypting a data base.
and i am stumped on this one.
all help is appreciated
thanks

[bennyandthejets]

You can determine whether or not a particular bit is turned on by using the & operator, ie:

if (value & 0x01)
if (value & 0x02)
if (value & 0x04)

if (value & pow(2,0))
if (value & pow(2,1))
if (value & pow(2,2))

To ensure a bit is turned on, do this:

value|=0x01;

To ensure it is off, do this:

value&=~(0x01);

Note that those last two code pieces will ensure the bit state no matter what it was orginally, so they're safe to use without first checking the state.

I suggest a function signature like this:

int SwapBits(int value, int index1,int index2);

Good luck. Have a shot, then post any problems you have.