Bitwise Exclusive OR
The bitwise Exclusive OR is True if either bits are set, but not both. The following shows the result of a bitwise Exclusive OR on the numbers 23 and 12.
10111 (23)
01100 (12) Exclusive OR (XOR)
_____________________________
11011 (result = 27) |
The Exclusive OR has some interesting properties. If you Exclusive OR a number by itself, it sets itself to zero as the zeros will remain zero and the ones can't both be set so are set to zero.
As a result of this, if you Exclusive OR a number with another number, then Exclusive OR the result with the other number again, the result is the original number. You can try this with the numbers used in the above example.
23 XOR 12 = 27
27 XOR 12 = 23
27 XOR 23 = 12
This feature can be used for encryption. The following program uses an encryption key of 23 to illustrate the property on a number entered by the user.
#include <stdio.h>
int main()
{
int num, key = 23;
printf("Enter a number: ");
scanf("%d", &num);
num ^= key;
printf("Exclusive OR with %d gives %d\n", key, num);
num ^= key;
printf("Exclusive OR with %d gives %d\n", key, num);
return 0;
}
Bitwise Compliment
The bitwise Compliment is a one's compliment operator that toggles the bit on or off. If it is 1, it will be set to 0, if it is 0 it will be set to 1.
#include <stdio.h>
int main()
{
int num = 0xFFFF;
printf("The compliment of %X is %X\n", num, ~num);
return 0;
}
|
