Why does this tread mix up its function parameters

Question

I have some work I want to run in seperate tasks, for demonstration purposes I simplied the code into just filling a list with the numbers 1 - 1000. This is what I try:

public struct ExampleStruct
        {
            public String number;
            public String otherData;
        }
List<String> results = new List<string>();
List<Task> TList = new List<Task>();

void mainFunc()
        {
            for(int i = 0; i < 1000; i++)
            {
                ExampleStruct.no = i.ToString();
                ExampleStruct.zip = "3333";
                TList.Add(Task.Run(() => GetDataFor(ExampleStruct)).ContinueWith(ct => incrementProgress(worker)));
            }
            Task.WaitAll(TList.ToArray());
        }

private void GetDataFor(ExampleStruct dataInput)
        {
            results.Add(dataInput.number.ToString());
        }

Now I get the following output in my list:

Why does this happen? Why are so many numbers skipped and the list ends up being filled with the last entry (999). I would expect an output just counting 1-1000, perhaps not in the right order if different threads dont start in order from 1-1000. Yet I expect every number to only occur once in the list.

I expect that the *variable* that contains an `ExampleStruct` (that appears to also be named `ExampleStruct`) is declared outside of the loop, but it's hard to tell since you *haven't included that variable in your example* — Damien_The_Unbeliever, Jan 20 '23 at 14:24

Why does this tread mix up its function parameters

0 Answers0