About Conditional Statements...

[edmundito]

Some programming languages allow you to do the following gimmick:

Code: ags

int *a;
(...)
if(a && *a > 5) {}

But I tried doing something similar on AGS and it broke! does it not have some sort of "short-circuit" mechanism? or do I have to do it this way:

Code: ags

if(a){
  if(*a >5) {}
}

Actually, what I did had nothing to do with pointer, what I checked for was if a property did not have a certain value and then if the player had the inventory with the property value... which broke when I didn't set a value to the property (default being -1)

[DoorKnobHandle]

Try this:

Code: ags

if(a > 5 && *a > 5) {}

Should work!

I tried doing something similar on AGS and it broke!

[edmundito]

this is what I did, though:

Code: ags

if(What.GetProperty("InvItem") >= 0 && player.InventoryQuantity[What.GetProperty("InvItem")] > 0)

But it still checks for player.InventoryQuantity[What.GetProperty("InvItem")]  even though it should have failed by What.GetProperty("InvItem") >= 0.

[strazer]

http://www.adventuregamestudio.co.uk/tracker.php?action=detail&id=509

[edmundito]

Ahh... thanks, Strazer. I guess I'm going to stop being lazy and do it right

actually, it would be nice if you someone could help me out on this one.. because this is what it's supposed to do:

Code: ags

if(What.GetProperty("InvItem") >= 0 && player.InventoryQuantity[What.GetProperty("InvItem")] > 0) {
  // success!
}
else {
  // display message saying that you can't do it
}

but if I change it to, then I have to do something silly like:

Code: ags

if(What.GetProperty("InvItem") >= 0) {
  if(player.InventoryQuantity[What.GetProperty("InvItem")] > 0) {
    // success!
    }
    else {
       // display message saying that you can't do it
    }
}
else {
  // display message saying that you can't do it AGAIN!!!
}

I'm a bit rusty (and lazy) on coding right now... I'm guessing that the other way is to do some sort of else-if or even an if statement. I'll think about it out some more.

[strazer]

How about this:

Code: ags

  bool success;

  if (What.GetProperty("InvItem") >= 0)
    if (player.InventoryQuantity[What.GetProperty("InvItem")] > 0)
      success = true;

  if (success == true) {
    // success!
  }
  else {
    // display message saying that you can't do it
  }

[Scummbuddy]

shouldn't it be with more parantheseses?

if ( (What.GetProperty("InvItem") ) >= 0 && ( player.InventoryQuantity[What.GetProperty("InvItem")] > 0)Ã,  )

[strazer]

Nope, that's not it.

Edit:

The expressions are still both evaluated.

But in general, it is indeed good practice to surround combined expressions with their own braces:

if ( (What.GetProperty("InvItem") >= 0) && (player.InventoryQuantity[What.GetProperty("InvItem")] > 0) ) {