I came across the following line
hsb.s = max != 0 ? 255 * delta / max : 0;
What do the ?
and :
mean in this context?
This question is related to
javascript
syntax
operators
conditional-operator
Properly parenthesized for clarity, it is
hsb.s = (max != 0) ? (255 * delta / max) : 0;
meaning return either
255*delta/max
if max != 00
if max == 0Be careful with this. A -1 evaluates to true although -1 != true and -1 != false. Trust me, I've seen it happen.
so
-1 ? "true side" : "false side"
evaluates to "true side"
?: is a short-hand condition for else {}
and if(){}
problems.
So your code is interchangeable to this:
if(max != 0){
hsb.s = 225 * delta / max
}
else {
hsb.s = 0
}
hsb.s = max != 0 ? 255 * delta / max : 0;
?
is a ternary operator. It works like an if
in conjunction with the :
!=
means not equals
So, the long form of this line would be
if (max != 0) { //if max is not zero
hsb.s = 255 * delta / max;
} else {
hsb.s = 0;
}
? :
isn't this the ternary operator?
var x= expression ? true:false
This is probably a bit clearer when written with brackets as follows:
hsb.s = (max != 0) ? (255 * delta / max) : 0;
What it does is evaluate the part in the first brackets. If the result is true then the part after the ? and before the : is returned. If it is false, then what follows the : is returned.
Source: Stackoverflow.com