How to pass arguments to thread in C#

c#, multithreading

Solution

You are creating a closure over the loop variable - an easy fix is to just create a local copy, so your thread uses the desired value:

void SetThread()
    {
        for (int i = 0; i < _intArrayLength; i++)
        {
           int currentValue = i;
            Console.Write(string.Format("SetThread->i: {0}\r\n", i));
            _th[i] = new Thread(() => RunThread(currentValue));
            _th[i].Start();
        }
    }

Problem

all I have searched this question, and I found so many answers to it was not difficult to find a solution for my question. BUT, I have strange experience and I don't know the reason that's why I ask people to give me some advice. Here are my codes: ``` void SetThread() { for (int i = 0; i < _intArrayLength; i++) { Console.Write(string.Format("SetThread->i: {0}\r\n", i)); _th[i] = new Thread(new ThreadStart(() => RunThread(i))); _th[i].Start(); } } void RunThread(int num) { Console.Write(string.Format("RunThread->num: {0}\r\n", num)); } ``` Yes, they are ordinary thread codes. I expect all the thread array should be calling RunThread method 10 times. It should be like ``` SetThread->i: 0 SetThread->i: 1 SetThread->i: 2 SetThread->i: 3 SetThread->i: 4 SetThread->i: 5 SetThread->i: 6 SetThread->i: 7 SetThread->i: 8 SetThread->i: 9 RunThread->num: 0 RunThread->num: 1 RunThread->num: 2 RunThread->num: 3 RunThread->num: 4 RunThread->num: 5 RunThread->num: 6 RunThread->num: 7 RunThread->num: 8 RunThread->num: 9 ``` This is what I expect to be. The order is not important. But I get the result like below. ``` SetThread->i: 0 SetThread->i: 1 SetThread->i: 2 The thread '<No Name>' (0x18e4) has exited with code 0 (0x0). The thread '<No Name>' (0x11ac) has exited with code 0 (0x0). The thread '<No Name>' (0x1190) has exited with code 0 (0x0). The thread '<No Name>' (0x1708) has exited with code 0 (0x0). The thread '<No Name>' (0xc94) has exited with code 0 (0x0). The thread '<No Name>' (0xdac) has exited with code 0 (0x0). The thread '<No Name>' (0x12d8) has exited with code 0 (0x0). The thread '<No Name>' (0x1574) has exited with code 0 (0x0). The thread '<No Name>' (0x1138) has exited with code 0 (0x0). The thread '<No Name>' (0xef0) has exited with code 0 (0x0). SetThread->i: 3 RunThread->num: 3 RunThread->num: 3 RunThread->num: 3 SetThread->i: 4 RunThread->num: 4 SetThread->i: 5 SetThread->i: 6 RunThread->num: 6 RunThread->num: 6 SetThread->i: 7 RunThread->num: 7 SetThread->i: 8 RunThread->num: 8 SetThread->i: 9 RunThread->num: 9 RunThread->num: 10 ``` What I expect is that RunThread function should carry the argument(num) from 0 to 9. And I cannot figure out what that error message is. "The thread '' ~~ and so on. Could anyone give me some clue on this?

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