InvalidOperationException: Collection was modified; enumeration operation may not execute.

Im getting errors on the foreach statement guys. can you help me?. sometimes it freezes unity

InvalidOperationException: Collection was modified; enumeration operation may not execute.

Code (csharp):

1.  
2. void GetWord(){
3.  
4.         matchedIndex = false;
5.  
6.         wordIndex = Random.Range(0, words.Length);
7.         generatedWord = words[wordIndex];
8.  
9.         foreach(string myString in usedWords){
10.             if(generatedWord == myString){
11.                 print("HAVE MATCHED");
12.                 matchedIndex = true;
13.                 GetWord();
14.             }
15.         }
16.  
17.         if(matchedIndex == false){
18.             usedWords.Add(generatedWord);
19.             WordMatching(generatedWord);
20.         }
21.     }
22.  

 

Your collection is being altered as you use it, you're adding to the list inside of a for each statement that is iterating through that list. A quick hack is to make a copy of this list before you start using it since the only other option is to rewrite the whole thing since your structure is flawed.

Also, wrong subforum.

Hack:

Code (csharp):

1. foreach(string myString in usedWords)

Code (csharp):

1. foreach(string myString in usedWords.ToList())

 

Code (CSharp):

1. for(int i=0;i<useWords.Lenght;++i)
2. {
3.             if(generatedWord == useWords[i])
4.             {
5.                 print("HAVE MATCHED");
6.                 matchedIndex = true;
7.                 GetWord();
8.             }
9. }

 

Use a for loop, instead of a foreach loop.
You can't set a new value to the iterated object.

 

IEnumerable guarantee that we can go through all elements, in order. However, if you remove an item, add an item, or change the order, this guarantee is broken. So it is not allowed.

Secondly, I know recursive functions are super cool and fun to make! Buuuuutttttt..... they are a good source of bugs. >.>

 

yes i got this one one this

twaypoints = new List<GameObject>(GameObject.FindGameObjectsWithTag("STR"));
int count = 0;
GameObject last = gameObject;
foreach (GameObject item in twaypoints) {

if (count!= 0)
last =item;
GameObject pobj = proche (last);
twaypoints.Remove(pobj);
waypoints.Add (pobj);
count +=1;
}

usedWords.ToList()) look not work

 

I was using a list and copied it to an array with .ToArray() and that worked

 

This sounds like a job for ... not recursion. Copying it to a separate list would make it work, technically, but you're still doing a bunch of looping and calls unnecessarily. What about:

Code (csharp):

1. void GetWord () {
2.   for(bool alreadyUsed = true; alreadyUsed;) {
3.      wordIndex = Random.Range(0,words.Length);
4.      generatedWord = words[wordIndex];
5.      alreadyUsed = usedWords.Contains(generatedWord);
6.   }
7.  
8.   usedWords.Add(generatedWord);
9.   WordMatching(generatedWord);
10. }

 

foreach (var item in lst.ToArray())
{

}

 

You da best <3

 

useWords.Length*

 

I had a similar problem, I used for() instad of foreach() and the problem solved.

 

I just did .ToArray() for it