-If- doesnt work in -void Update-

Hello, all. Could you please tell me whats my mistake in the code.

In this code:

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class Patrol : MonoBehaviour
6. {
7.     public float speed;
8.     public Transform[] moveSpots2;
9.     public Transform[] moveSpotsP;
10.     private float waitTime;
11.     private int randomSpot2;
12.     private int randomSpotP;
13.     public float startWaitTime;
14.     public Transform ball;
15.     public GameObject enemy;
16.  
17.     void Start()
18.     {
19.  
20.         waitTime = startWaitTime;
21.         randomSpot2 = Random.Range(0, moveSpots2.Length);
22.         randomSpotP = Random.Range(0, moveSpotsP.Length);
23.         GameObject enemy = this.GetComponent<GameObject>();
24.     }
25.  
26.     void Update()
27.     {
28.  
29.         transform.LookAt(ball);
30.      
31.         if (enemy.transform.position.x > 0 & enemy.transform.position.z < 0)
32.         {
33.             transform.position = Vector3.MoveTowards(transform.position, enemy.transform.position, speed * Time.deltaTime);
34.         }
35.  
36.  
37.         if (enemy.transform.position.x < 0 & enemy.transform.position.z < 0 | enemy.transform.position.x > 0 & enemy.transform.position.z > 0)enemy.transform.position.x < 0 & enemy.transform.position.z > 0)
38.         {
39.             transform.position = Vector3.MoveTowards(transform.position, moveSpotsP[randomSpotP].position, speed * Time.deltaTime);
40.  
41.             if (Vector3.Distance(transform.position, moveSpotsP[randomSpotP].position) < 0.1f)
42.             {
43.  
44.                 if (waitTime <= 0)
45.                 {
46.  
47.                     randomSpotP = Random.Range(0, moveSpotsP.Length);
48.                     waitTime = startWaitTime;
49.                 }
50.  
51.                 else
52.                 {
53.                     waitTime -= Time.deltaTime;
54.                 }
55.  
56.             }
57.            
58.  
59.  
60.             if (enemy.transform.position.x < 1 & enemy.transform.position.z > 1)
61.             {
62.  
63.                 transform.position = Vector3.MoveTowards(transform.position, moveSpots2[randomSpot2].position, speed * Time.deltaTime);
64.  
65.                 if (Vector3.Distance(transform.position, moveSpots2[randomSpot2].position) < 0.1f)
66.                 {
67.  
68.                     if (waitTime <= 0)
69.                     {
70.  
71.                         randomSpot2 = Random.Range(0, moveSpots2.Length);
72.                         waitTime = startWaitTime;
73.                     }
74.  
75.                     else
76.                     {
77.                         waitTime -= Time.deltaTime;
78.                     }
79.  
80.  
81.  
82.                 }
83.             }
84.  
85.         }
86.     }
87.        
88.    

doesnt work this part of code:

Code (CSharp):

1. if (enemy.transform.position.x < 1 & enemy.transform.position.z > 1)
2.             {
3.  
4.                 transform.position = Vector3.MoveTowards(transform.position, moveSpots2[randomSpot2].position, speed * Time.deltaTime);
5.  
6.                 if (Vector3.Distance(transform.position, moveSpots2[randomSpot2].position) < 0.1f)
7.                 {
8.  
9.                     if (waitTime <= 0)
10.                     {
11.  
12.                         randomSpot2 = Random.Range(0, moveSpots2.Length);
13.                         waitTime = startWaitTime;
14.                     }
15.  
16.                     else
17.                     {
18.                         waitTime -= Time.deltaTime;
19.                     }

when Enemy position =

"enemy.transform.position.x < 1 & enemy.transform.position.z > 1"

Player doesnt move. But if Enemie's position not = abovementioned position so my Player is moving.

 

First off, there's very few places where you should use & instead of && in conditional checks (outside of bitwise operations). The former will evaluate both statements every time, whereas the latter won't bother evaluating the second statement if the first is False (this is called "short-circuiting")- this cuts down the work being done in many instances, and thus the processing time, especially when you can arrange statements so that the cheapest evaluation is first and it doesn't bother with more expensive evaluations if that one is False.

Line 37 above looks like it shouldn't even compile, because there seems to be an extra closing parenthesis in there without an open parenthesis. You should be more consistent with parentheses to be more exact about the order of operations you intend in conditionals when you have more than 2 statements that need to be evaluated.

Code (csharp):

1. if (enemy.transform.position.x < 0 & enemy.transform.position.z < 0 | enemy.transform.position.x > 0 & enemy.transform.position.z > 0)
2.  
3. // should probably be more like
4.  
5. if ((enemy.transform.position.x < 0 && enemy.transform.position.z < 0) || (enemy.transform.position.x > 0 && enemy.transform.position.z > 0))

In this particular case though, it looks like line 37 can be simplified to:

Code (csharp):

1. if (!(enemy.transform.position.x > 0 && enemy.transform.position.z < 0))

... since that seems to be the only criteria you're trying to avoid there.

I would also cache the enemy.transform into a local reference before all of this and use that instead- all of these enemy.transform calls are actually using enemy.GetComponent<Transform>(), and this gets to be a little expensive when doing it potentially dozens of times in a single function. If you do:

Code (csharp):

1. var enemyTransform = enemy.transform;

... then use enemyTransform instead, you can avoid all of those calls. The same goes for the transform references to the current GameObject's transform component.

You should also get used to using if/else if instead of a series of independent if statements, to again cut down on the work being done and the potential for mistakes. If the first if statement comes back as true, is there a point in evaluating the rest of the statements? if/else if will just skip the rest after it finds a match, which seems appropriate here.

I can't actually tell you the exact cause of the problem you're having, because everything's sort of a mess. I hope some of that helps to clean it up and possibly even fix the issue though.

 

I think I remember there being short-circuiting vs not-short-circuiting operators in other languages, but that's not actually how it works in C#. In C#, & and && are completely different things. & is a bit-wise operation performed on integers, while && is used to test for the conjuction of two boolean values.

So, to the OP, using & is complete wrong in this case, and it doesn't mean "this and that" in the sense you're trying to use it. Instead, it means, "Take the integer values of the numbers on either side of the &, and return a new integer that shows all the bits those two numbers have in common."

So, in short, && is generally used to test whether two things are both true, while & is usually used to see if a number matches a certain bitwise mask.

 

@dgoyette It works that way in C# as well. Bitwise operations are for integral types, while booleans evaluate both sides. Here's the documentation if you're curious. =)

 

That's an interesting inconsistency, that they chose to have && short-circuit but not &. Definitely something to keep in mind. Thanks.

 

It's actually a useful distinction in cases where the evaluating statement/function also changes something (x > y++), though I would argue that's not really good programming practice.

 

Awesome! My problem solved.

Thanks a lot.