C: XNOR / Exclusive-Nor gate?

Question

I am trying to find the most effective way of writing a XNOR gate in C. if(VAL1 XNOR VAL2) { BLOCK; } Any suggestions? Thanks.

Answer 1

An XNOR gate's truth table is the opposite of XOR:

A B XNOR

F F T

F T F

T F F

T T T

Looking at the table, you can see that it is true if the two inputs are the same, and false if the two inputs are different.

So assuming that your inputs are known to be just Boolean true/false or 0/1 values, I think the easiest representation in C would be to use the == operator:

if (val1 == val2) {

BLOCK

}

Answer 2

//Macro

#define XNOR( val1, val2) ( ((val1)==(val2) ) ? (1) : (0) )

//function

int XNOR ( int val1 , int val2)

{

return( ((val1)==(val2) ) ? 1 : 0 );

}

// If you have C++ you can inline the function