Question

#include <iostream>
#include <iomanip>
#include <stdio.h>
#include <windows.h>
#include <process.h>

using namespace std;
HANDLE ghEvents;


struct DataStructure
{
int r[2];
int h;
};


unsigned __stdcall f2(void *p)
{

DataStructure *input = (DataStructure *)p;
int i = (int)input->h;
cout <<i<<endl;

}   


int main()
{

HANDLE hThread[8];
DWORD i, dwEvent, dwThreadID;
unsigned threadID;
DataStructure input;

ghEvents = CreateEvent(NULL,FALSE,FALSE,NULL);  

for (int i = 0; i < 8; i++) 
{   
input.h=i;
hThread[i] = (HANDLE)_beginthreadex( NULL, 0, f2, (void*)&input, 0, &threadID );
}

dwEvent = WaitForMultipleObjects(8,hThread,TRUE,INFINITE);       

CloseHandle(ghEvents); 
for (int i = 0; i < 8; i++) 
{
CloseHandle( hThread[i] );
}

cin.get();
return 0;

}

The output is 77777777 instead of 12345678.

I know i have to pass the input by value and not reference but it keeps giving me an error message, what is the proper way to do it?

Answer 1

This is subsequent to my previous answer as is a better solution if the number of threads is known at compile time.

DataStructure input[8];  

... 

for (int i = 0; i < 8; i++)   
{     
   input[i].h=i;  
   hThread[i] = (HANDLE)_beginthreadex( NULL, 0, f2, (void*)&input[i], 0, &threadID );  
} 

And you need to return a value:

unsigned __stdcall f2(void *p)      
{      

   DataStructure *input = (DataStructure *)p;      
   int i = input->h;      
   cout <<i<<endl;      
   return 0; 
}