CODEWITHSUNDEEP
cmultithreadingparametersarguments
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Reputation: 31

Threading in C on windows, how to pass parameters?

I'm looking on how to use threads in C language. I found how to use it on windows but I don't know why it just doesn't work on my computer as it should ...

First thing: I know that I have to create a struct to use parameters, so here's my struct:

typedef struct monclient
{
    SOCKADDR_IN _csin;
    char _ip[30];
    int _port;
    char _name[255];
    int _taille;
    monclient* _next;
    int _justconnected;

}client;

My header.h file:

#pragma once
#include<stdio.h>
#include<winsock2.h>
#include <windows.h>
#include "Structures.h"
#pragma warning (disable:4996)
#pragma comment(lib,"ws2_32.lib") //Winsock Library
DWORD WINAPI ThreadProc(LPVOID lpParameter); //Prototype to be used everywhere in code

Here's what you need to know about my main():

void main()
{
    client* mesclients = (client*)malloc(sizeof(client));
    //I'm filling informations ...
    thread = CreateThread(NULL, 0, ThreadProc, &mesclients, 0, NULL);
    if(thread)
    {printf("success\n");
    }
    else
    {
    printf("problem\n");
    }
}

and now most important: my thread

#include "Header.h"
DWORD WINAPI ThreadProc(LPVOID lpParameter)
{
    client* test = (client*)lpParameter;
    printf("%s", test->_name);
    // I CANT RETURN THE NAME ... ALL THE VALUES ARE RANDOM IT SEEMS LIKE HE CANT ACCESS THE ORIGINAL   POINTER
    return 0;
}

If someone could explain what is going wrong here it would be awesome ! I think I sent the adress of my pointer so it becomes a pointer of pointer but I'm not sure about it... Maybe it's just a reference here. Thanks for further help.

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Upvotes: 0

Views: 315

Answers (1)

dash-o
dash-o

Reputation: 14491

The code send the address of the mesclients to the thread, which is a variable on the main stack. You want to send the address of the client object that was malloc-ed.

    thread = CreateThread(NULL, 0, ThreadProc, mesclients, 0, NULL);

Upvotes: 1

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