Is there a better way of writing v = (v == 0 ? 1 : 0); [closed]
I want to toggle a variable between 0 and 1. If it’s 0 I want to set it to 1, else if it’s 1 I want to set it to 0.
This is such a fundamental operation that I write so often I’d like to investigate the shortest, clearest possible way of doing it. Here’s my best so far:
v = (v == 0 ? 1 : 0);
Can you improve on this?
Edit: the question is asking how to write the above statement in the fewest characters while retaining clarity – how is this ‘not a real question’? This wasn’t intended to be a code-golf exercise, though some interesting answers have come out of people approaching it as golf – it’s nice to see golf being used in a constructive and thought-provoking manner.
You can simply use:
v = 1 - v;
This of course assumes that the variable is initialised properly, i.e. that it only has the value 0 or 1.
Another method that is shorter but uses a less common operator:
v ^= 1;
To be clear; I never approached this question as code golf, just to find a short way of doing the task without using any obscuring tricks like side effects of operators.
0 is a
false value and
1 is a
v = (v ? 0 : 1);
If you are happy to use
false instead of numbers
v = !v;
or if they must be numbers:
v = +!v; /* Boolean invert v then cast back to a Number */
v = (v + 1) % 2 and if you need to cycle through more values just change
(n + 1). Say you need to cycle 0,1,2 just do
v = (v + 1) % 3.
You could write a function for it and use it like:
v = inv(v)
If you don’t care about any possibility other than 1:
v = v ? 0 : 1;
In the above case, v will end up being 1 if v is 0, false, undefined or null. Take care using this kind of approach – v will be 0 even if v is “hello world”.
v = 1 - v, or
v ^= 1 or
v= +!v will all get the job done, but they constitute what I would refer to as hacks. These are not beautiful lines of code, but cheap tricks to have the intended effect.
1 - v does not communicate “toggle the value between 0 and 1”. This makes your code less expressive and introduces a place (albeit a small one) where another developer will have to parse your code.
Having instead a function like
v = toggle(v) communicates the intent at the quickest glance.