c++ multithread array
- by user1731972
i'm doing something for fun, trying to learn multithreading
Problems passing array by reference to threads
but Arno pointed out that my threading via process.h wasn't going to be multi-threaded.
What I'm hoping to do is something where I have an array of 100 (or 10,000, doesn't really matter I don't think), and split up the assignment of values to each thread. Example, 4 threads = 250 values per thread to be assigned.
Then I can use this filled array for further calculations.
Here's some code I was working on (which doesn't work)
#include <process.h>
#include <windows.h>
#include <iostream>
#include <fstream>
#include <time.h>
//#include <thread>
using namespace std;
void myThread (void *dummy );
CRITICAL_SECTION cs1,cs2; // global
int main()
{
ofstream myfile;
myfile.open ("coinToss.csv");
int rNum;
long numRuns;
long count = 0;
int divisor = 1;
float holder = 0;
int counter = 0;
float percent = 0.0;
HANDLE hThread[1000];
int array[10000];
srand ( time(NULL) );
printf ("Runs (use multiple of 10)? ");
cin >> numRuns;
for (int i = 0; i < numRuns; i++)
{
//_beginthread( myThread, 0, (void *) (array1) );
//???
//hThread[i * 2] = _beginthread( myThread, 0, (void *) (array1) );
hThread[i*2] = _beginthread( myThread, 0, (void *) (array) );
}
//WaitForMultipleObjects(numRuns * 2, hThread, TRUE, INFINITE);
WaitForMultipleObjects(numRuns, hThread, TRUE, INFINITE);
}
void myThread (void *param )
{
//thanks goes to stockoverflow
//http://stackoverflow.com/questions/12801862/problems-passing-array-by-reference-to-threads
int *i = (int *)param;
for (int x = 0; x < 1000000; x++)
{
//param[x] = rand() % 2 + 1;
i[x] = rand() % 2 + 1;
}
}
Can anyone explain why it isn't working?
