Re: simple pthread

From:

"io_x" <a@b.c.invalid>

Newsgroups:

comp.lang.c++

Date:

Tue, 26 Jul 2011 10:31:03 +0200

Message-ID:

<4e2e7ad0$0$15664$4fafbaef@reader2.news.tin.it>

"io_x" <a@b.c.invalid> ha scritto nel messaggio
news:4e2e730d$0$44198$4fafbaef@reader1.news.tin.it...

"cerr" <ron.eggler@gmail.com> ha scritto nel messaggio
news:d7dba757-ed45-4a21-b086-e4b62b363e1d@u6g2000prc.googlegroups.com...
i have now something like this:
int MyThread::StartMe(void)
{
// starting thread
pthread_create(&ThreadA, NULL, &PrintMsg, NULL);

}
//-------------------------------------------------------------

void PrintMsg(void)
{
//thread function
while (1) {

   pthread_mutex_lock( &mutex1 );
   count++;
   pthread_mutex_unlock( &mutex1 );

   cout << "I Incremented count: " << count << endl;
}
}
but I get following:

$ g++ -pthread -o example example.cpp
example.cpp: In member function ?int MyThread::StartMe()?:
example.cpp:66:49: error: invalid conversion from ?void (*)()? to
?void* (*)(void*)?
example.cpp:66:49: error: initializing argument 3 of ?int
pthread_create(pthread_t*, const pthread_attr_t*, void* (*)(void*),
void*)?

How do I gwet this compiled? How do I pass a void argument?
Thank you!
-------------------
i modify somthing; in printmsg i impose count<100000

unsigned count=0;

void* PrintMsg(void* unused)
{(void) unused;
//thread function
while (1)
{ pthread_mutex_lock( &mutex1 );
   count++;
   pthread_mutex_unlock( &mutex1 );

   cout << "I Incremented count: " << count << endl;
   if(count>=100000) break;
}
return 0;
}

void MyThread::StartMe(void)
{// starting thread
pthread_create(&ThreadA, 0, &PrintMsg, 0);
}

i forget that it is output that has need mutex;
but where are the headers i has to link with this?

unsigned count=0;
unsigned index=-1;
unsigned array[256];

void* PrintMsg(void* a)
{//thread function
unsigned aa;

aa=*(unsigned*)a
  while (1)
  { pthread_mutex_lock( &mutex1 );
    count++;
    cout << "Tread number=" << aa << "; ";
    cout << "I Incremented count: " << count << "\n";
    pthread_mutex_unlock( &mutex1 );

    if(count>=100000) break;
  }
return 0;
}

void StartMe(int i)
{// starting thread
++index; index&=255; array[index]=i;
pthread_create(&ThreadA, 0, &PrintMsg, (void*)(array+index));
}

int main(void)
{int i;
for(i=0; i<100; ++i)
       StartMe(i);
}