What's this? .Pos.Y += (up) ? step : -step;

[jfisher446]

...[index].Pos.Y += (up) ? step : -step;

General question here. I have NO idea how I'd begin to look this up so if someone could explain the (up), ?, and : portions of this that would be great. up is a bool that's passed in, but why's it in () and how's it used to perform what seems like a math calculation, and I've never encountered the ? or : used like this before. step is how many units to move a vertex I know but the rest is confusing the hell out of me.

Edit: wait. is it sort of an inline if-then-else statement? if up is true, then use a positive step value, otherwise (:) use a negative one?

[REDDemon]

you can write it also as:

Code: Select all

if(up)
{
    [index].Pos.Y +=step;
}
else
{
    [index].Pos.Y -= step;
}

yes it is a if-than-else statement, sometimes is usefull using it. usually is not used very often.

[randomMesh]

http://en.wikipedia.org/wiki/Ternary_operation
http://en.wikipedia.org/wiki/%3F:

[Brainsaw]

I like this statement. I often use if for debug printing, e.g.

Code: Select all

printf("some string=\"%s\"\n",someString!=NULL?someString:"NULL");

or in return statements, e.g. in getter methods

Code: Select all

myObject *getObjectAtIndex(u32 index) {
  return index<objectArray.size()?objectArray[index]:NULL;
}

[jfisher446]

Wow, thanks guys. Never would have thought to look up ternary operations and probably a longer shot searching wikipedia for '?'... I appreciate the help. And thanks Brainsaw for the tip, I can see the usefulness

[Luben]

If i'm not mistaken, it's also possible to use it like this

Code: Select all

 int x=5, y=6;
 bool storeinx=true;
 (storeinx?x:y) = 4;

I cant access codepad atm so i cant check it. If i remember correctly one can get some amusing behaviours from different compilers when using the ternary operator like this.