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problem with multithreading!!!

hahaha12a2 (1)
Hello everyone!!
I must finish an exercise :" writing a program that use multithreading to slove matrix multiplication "
I have Matrix A (dim1*dim2) and matrix B(dim3*dim4).Matrix C=A*B.
I used dim1*dim4 threads to calculate matrix C.
I just finished my code but it have a problem with WaitForMultipleObjects() Function.
I use this function to make main thread wait all worker thread before printing the output.
This function didn't work.
My code below:
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#include <iostream>
#include <fstream>
#include <stdio.h>
#include <conio.h>
#include <windows.h>
using namespace std;
#define max 50
int a[max][max];
int b[max][max];
int c[max][max];
int dim1;
int dim2;
int dim3;
int dim4;
struct v
{
	int i;

	int j;
};

typedef v* pv;

DWORD WINAPI result_rowi_columnj(LPVOID);


void main()
{
	ifstream inFileA;
	 
	inFileA.open("matrixA.txt");
	inFileA>>dim1;
	inFileA>>dim2;

	for(int i=0;i<dim1;i++)
		for(int j=0;j<dim2;j++)
		{
			inFileA>>a[i][j];
		}
	inFileA.close();

	///////////////////////////////////////////////////////
	ifstream inFileB;
	
	inFileB.open("matrixB.txt");
	inFileB>>dim3;
	inFileB>>dim4;
	for(int i=0;i<dim3;i++)
		for(int j=0;j<dim4;j++)
		{
			inFileB>>b[i][j];
		}
	inFileB.close();
	///////////////////////////////////////////////////////////////////////////
	cout<<endl<<" matrix A:"<<endl;
	for(int i=0;i<dim1;i++)
	{
		for(int j=0;j<dim2;j++)
		cout<<"  "<<a[i][j];
		cout<<endl;
	}
	cout<<endl<<" matrix B:"<<endl;
	for(int i=0;i<dim3;i++)
	{
		for(int j=0;j<dim4;j++)
		cout<<"  "<<b[i][j];
		cout<<endl;
		
	}////////////////////////////////////////////////////////////////////////////

HANDLE* hThread = new HANDLE[dim1 * dim4];
DWORD *pThreadID= new DWORD[dim1*dim4];
pv arraypos= new v[dim1*dim4];
DWORD state;


for(int i=0;i<dim1;i++)
		for(int j=0;j<dim4;j++)
		{

			arraypos[i*dim1+j].i=i;
			arraypos[i*dim1+j].j=j;
			hThread[i*dim1+j]=CreateThread(NULL,0,result_rowi_columnj,(arraypos+i*dim1+j),0,&pThreadID[i*dim1+j]);
					if (hThread[i*dim1+j])
					printf ("..................Thread  %d  launched successfully.....\n",i*dim1+j);// Create dim1*dim4 thread to calculate matrix C
					
		}

WaitForMultipleObjects(dim1 * dim4, hThread, TRUE, INFINITE);// main thread wait all worker thread, after that it prints output, BUT this function didn't work.
		
			
	
	/////////////////////////// MAtrix C//////////////////////////////////


	ofstream outFile;
	outFile.open("output.txt");
	outFile<<dim1<<" "<<dim4<<endl;
	for(int i=0;i<dim1;i++)
	{
		for(int j=0;j<dim4;j++)
		outFile<<c[i][j]<<" ";
		outFile<<endl;
		
	}
	outFile.close();
/////////////////////////////////////////////////////

		
for(int i = 0; i < dim1 * dim4; i++)
			CloseHandle(hThread[i]);
delete [] hThread;
delete [] arraypos;
delete [] pThreadID;



}


DWORD WINAPI result_rowi_columnj(LPVOID lpara)
{

	pv pos=(pv)lpara;
	c[pos->i][pos->j]=0;
	for(int k=0;k<dim2;k++)
			c[pos->i][pos->j]+=(a[pos->i][k]*b[k][pos->j]);
			return 0;
}


I don't know how to slove this problem and hope someone help me.
Thank you very much
kbw (9488)
This might help, it's a multithreaded dot product example.
http://www.cplusplus.com/forum/beginner/20372/#msg106339
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