C++ WIN32: Short multitasking example

Question

I searched for examples on how to create a simple multithreaded app that does something similar to this:

#include <iostream>
using namespace std;
int myConcurrentFunction( )
{
    while( 1 )
    {
         cout << "b" << endl;
    }
}
int main( )
{
    // Start a new thread for myConcurrentFunction
    while( 1 )
    {
         cout << "a" << endl;
    }
}

• How can I get the above to output a and b "randomly" by starting a new thread instead of just calling myConcurrentFunction normally?

I mean: What is the minimal code for it? Is it really only one function I have to call? What files do I need to include?

I use MSVC 2010, Win32

Answer 1

The easiest is _beginthread. Just focus on how they create the thread in their example, it's not as complicated as it seems at a first glance.

#include <iostream>
#include <process.h>

using namespace std;
void myConcurrentFunction(void *dummy)
{
    while( 1 )
    {
         cout << "b" << endl;
    }
}

int main( )
{
    _beginthread(myConcurrentFunction, 0, NULL);
    while( 1 )
    {
         cout << "a" << endl;
    }
}

Answer 2

It is more complicated than that. For one, the thread function must return a DWORD, and take an LPVOID parameters.

Take a look at the code from MSDN for more details.

Answer 3

BTW, why thread when you just need random sprinkiling of 'a' & 'b'.

int randomSprinkling() { char val[2]={'a','b'};

int i = 0;
while( ++i < 100  ) 
{
    std::cout << val[rand()%2] << std::endl; 
} 
return 0;

}