XOR Boolean

[Buck Turgidson]

Can someone check me on if the following two blocks are logically
equivalent? Is there an even better way to write this with a one-liner?



return (inverse ^ line_matched);


// and

if ( !inverse )
return line_matched;
else
return !line_matched;

 

[Kristoffel]

Can someone check me on if the following two blocks are logically
equivalent? Is there an even better way to write this with a one-liner?



return (inverse ^ line_matched);


// and

if ( !inverse )
return line_matched;
else
return !line_matched;

() means if:
if there are different the result is false else true

so in one line :
(inverse ^ line_matched) ? return false : return true;

I think that the two blocks aren't logically equivalent .

K

 

[Kristoffel]

Can someone check me on if the following two blocks are logically
equivalent? Is there an even better way to write this with a one-liner?



return (inverse ^ line_matched);


// and

if ( !inverse )
return line_matched;
else
return !line_matched;

(inverse ^ line_matched) means if:
if there are different the result is false else true

so in one line :
(inverse ^ line_matched) ? return false : return true;

I think that the two blocks aren't logically equivalent .

K

 

[=?ISO-8859-1?Q?Daniel_Sj=F6blom?=]

Can someone check me on if the following two blocks are logically
equivalent?

Sure. Write some truth tables.

Is there an even better way to write this with a one-liner?

return (inverse ^ line_matched);

inv ^ line ->

line=1 line=0
inv=1 0 1
inv=0 1 0

// and

if ( !inverse )
return line_matched;
else
return !line_matched;

!inv ? line : !line ->

line=1 line=0
inv=1 0 1
inv=0 1 0

So yes, they are equivalent if I remember my logic right. There is
probably nothing better. An XOR is one of the cheapest operations on
most processors.

 

[Chris Riesbeck]

(inverse ^ line_matched) means if:
if there are different the result is false else true

just the opposite -- X ^ Y is true if X and Y are different,
i.e., exactly 1 is true

so in one line :
(inverse ^ line_matched) ? return false : return true;

anything ? return false : return true;

can always be written more briefly

return !anything;

 

[Chris Riesbeck]

Can someone check me on if the following two blocks are logically
equivalent?

==

 

[Joona I Palaste]

just the opposite -- X ^ Y is true if X and Y are different,
i.e., exactly 1 is true

anything ? return false : return true;

can always be written more briefly

return !anything;

And that way it'll even compile and everything. The operands of the ?:
operator have to be expressions, and return is not an expression.

--
/-- Joona Palaste ([email protected]) ------------- Finland --------\
\-- http://www.helsinki.fi/~palaste --------------------- rules! --------/
"I said 'play as you've never played before', not 'play as IF you've never
played before'!"
- Andy Capp

 

[Roedy Green]

return (inverse ^ line_matched);

Most programmers are terrified of xor. You can write that in a way
more familiar to the peanut gallery with:


return inverse != line_matched;

presuming both are booleans, not ints.

 

[Roedy Green]

so in one line :
(inverse ^ line_matched) ? return false : return true;

Why bother with ?. You already have a boolean.

 

[Kristoffel]

just the opposite -- X ^ Y is true if X and Y are different,
i.e., exactly 1 is true

rigth, I was wrong.