Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people, just like you, are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
Solved

Problems with && and ||

Posted on 2004-04-01
6
210 Views
Last Modified: 2012-05-04
Im having some strange issues with && and ||

In one instance, for example, the following code:

(players starts off at 0,0 and wants to move to a further point, say 100,100)

**
if ((movetox!=playerx) && (movetoy!=playery))  {
<playerx and player increased if needed>
}
**

Which will work fine until the playerx OR playery hit movetox/movetoy
Whereas

**
if ((movetox==playerx) && (movetoy==playery))  { }
else {
<playerx and player increased if needed>
}
**
works fine all the time? (i can get the code to work like that, but i dont like it)
later on, i have

**
if ((shotx[s]==shotgox[s]) && (shoty[s]==shotgoy[s])) { shots[s]=0; }
**

which basically kills off a bullet when it reaches it destination
but it doesnt seem to register at all when the variables hit 0
if i change the && to || itll work, but will kill a bullet when any axis is correct, rather than both

its been happening all over the place.

The whole code is a bit much, but ill try and replicate it into something smaller if i can and post that
I have absolutely no idea whats going on :(

THanks in advance
0
Comment
Question by:hippydaz
  • 2
  • 2
  • 2
6 Comments
 

Author Comment

by:hippydaz
ID: 10732212
ok, ignore the

if ((shotx[s]==shotgox[s]) && (shoty[s]==shotgoy[s])) { shots[s]=0; }

problem, that was just me being an idiot


the primary != && != problem still remains however
0
 
LVL 37

Accepted Solution

by:
zzynx earned 75 total points
ID: 10732214
Some logic:

The inverse of

[1] if ( a==A && b==B )

                                                  with inverse I mean:  if ( !(a==A && b==B) )

is

[2] if ( a!=A || b!=B )        


Look at this table to understand:
       
a =    A   A  C  C
b =    C   B   B  C

[1] =  0   1   0  0
[2] =  1   0   1  1

But maybe that's not your problem.
0
 

Author Comment

by:hippydaz
ID: 10732255
My problem is that im an idiot :/

That worked zzynx, ta, points to you.

I dont see why it works, offhand, ill have a look later and try and understand.

Thanks
0
Free Tool: Path Explorer

An intuitive utility to help find the CSS path to UI elements on a webpage. These paths are used frequently in a variety of front-end development and QA automation tasks.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

 
LVL 20

Expert Comment

by:Venabili
ID: 10732279
Well I am lost in your explanation butr basically;

If you have a && b - it is true only if a and b are true together
|| needs one of the arguments to be true so that it is true

What exactly you need?
0
 
LVL 20

Expert Comment

by:Venabili
ID: 10732300
I knew I have slow internet today:)
Glad that you already solved the trouble
0
 
LVL 37

Expert Comment

by:zzynx
ID: 10732311
Thanks for accepting.
That keeps us going on.
:)
0

Featured Post

Free Tool: ZipGrep

ZipGrep is a utility that can list and search zip (.war, .ear, .jar, etc) archives for text patterns, without the need to extract the archive's contents.

One of a set of tools we're offering as a way to say thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

In this post we will learn how to connect and configure Android Device (Smartphone etc.) with Android Studio. After that we will run a simple Hello World Program.
Basic understanding on "OO- Object Orientation" is needed for designing a logical solution to solve a problem. Basic OOAD is a prerequisite for a coder to ensure that they follow the basic design of OO. This would help developers to understand the b…
Viewers learn about the third conditional statement “else if” and use it in an example program. Then additional information about conditional statements is provided, covering the topic thoroughly. Viewers learn about the third conditional statement …
Viewers learn about the “while” loop and how to utilize it correctly in Java. Additionally, viewers begin exploring how to include conditional statements within a while loop and avoid an endless loop. Define While Loop: Basic Example: Explanatio…

791 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question