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simple pthread

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  simple pthread cerr <ron.eggler@gmail.com> - 2011-07-25 20:45 -0700
    Re: simple pthread red floyd <no.spam.here@its.invalid> - 2011-07-25 20:55 -0700
    Re: simple pthread Ian Collins <ian-news@hotmail.com> - 2011-07-26 15:56 +1200
    Re: simple pthread "Alf P. Steinbach" <alf.p.steinbach:usenet@gmail.com> - 2011-07-26 08:28 +0200
      Re: simple pthread cerr <ron.eggler@gmail.com> - 2011-07-25 23:31 -0700
        Re: simple pthread cerr <ron.eggler@gmail.com> - 2011-07-25 23:53 -0700
          Re: simple pthread Ian Collins <ian-news@hotmail.com> - 2011-07-26 19:43 +1200
          Re: simple pthread "io_x" <a@b.c.invalid> - 2011-07-26 09:57 +0200
            Re: simple pthread "io_x" <a@b.c.invalid> - 2011-07-26 10:31 +0200
              Re: simple pthread "io_x" <a@b.c.invalid> - 2011-07-26 12:38 +0200
                Re: simple pthread Ian Collins <ian-news@hotmail.com> - 2011-07-26 22:39 +1200
            Re: simple pthread Ian Collins <ian-news@hotmail.com> - 2011-07-26 22:41 +1200

#8224 — simple pthread

hi There,

I'm just trying to write a little sample program with a thread. I can't get my thread started and am not sure why, I get 
$ g++ -o example example.cpp
example.cpp: In member function ‘int MyThread::StartMe()’:
example.cpp:42:59: error: expected primary-expression before ‘void’
example.cpp:42:63: error: initializer expression list treated as compound expression
the code:
int MyThread::StartMe(void)
{
  int pthread_create(&ThreadA, NULL, &MyThread::PrintMsg, void);
}
//-------------------------------------------------------------

void MyThread::PrintMsg(void)
{
  cout << "I Incremented count: " << count << endl;
}

Can anyone point it out? I'm like HUH???

Thanks,

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#8225

On 7/25/2011 8:45 PM, cerr wrote:
> hi There,
>
> I'm just trying to write a little sample program with a thread. I can't get my thread started and am not sure why, I get
> $ g++ -o example example.cpp
> example.cpp: In member function ‘int MyThread::StartMe()’:
> example.cpp:42:59: error: expected primary-expression before ‘void’
> example.cpp:42:63: error: initializer expression list treated as compound expression
> the code:
> int MyThread::StartMe(void)
> {
>    int pthread_create(&ThreadA, NULL,&MyThread::PrintMsg, void);
get rid of "int"

> }
> //-------------------------------------------------------------
>
> void MyThread::PrintMsg(void)
> {
>    cout<<  "I Incremented count: "<<  count<<  endl;
> }
>
> Can anyone point it out? I'm like HUH???
>
> Thanks,

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#8226

On 07/26/11 03:45 PM, cerr wrote:
> hi There,
>
> I'm just trying to write a little sample program with a thread. I can't get my thread started and am not sure why, I get
> $ g++ -o example example.cpp
> example.cpp: In member function ‘int MyThread::StartMe()’:
> example.cpp:42:59: error: expected primary-expression before ‘void’

void is a type, you can't pass a type as a parameter!

> example.cpp:42:63: error: initializer expression list treated as compound expression
> the code:
> int MyThread::StartMe(void)
> {
>    int pthread_create(&ThreadA, NULL,&MyThread::PrintMsg, void);

This looks like a mixed up function declaration!


int something = pthread_create(  );

A decent compiler should tell you that MyThread::PrintMsg is the wrong 
function type for the function pointer parameter of pthread_create.

> }
> //-------------------------------------------------------------
>
> void MyThread::PrintMsg(void)
> {
>    cout<<  "I Incremented count: "<<  count<<  endl;
> }
>
> Can anyone point it out? I'm like HUH???
>
> Thanks,


-- 
Ian Collins

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#8232

On 26.07.2011 05:45, cerr wrote:
>
> I'm just trying to write a little sample program with a thread. I can't get my thread started and am not sure why, I get
> $ g++ -o example example.cpp
> example.cpp: In member function ‘int MyThread::StartMe()’:
> example.cpp:42:59: error: expected primary-expression before ‘void’
> example.cpp:42:63: error: initializer expression list treated as compound expression
> the code:
> int MyThread::StartMe(void)
> {
>    int pthread_create(&ThreadA, NULL,&MyThread::PrintMsg, void);

`void` is a type.


Cheers &  hth.,

- Alf

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#8233

On Jul 25, 11:28 pm, "Alf P. Steinbach"
<alf.p.steinbach:use...@gmail.com> wrote:
> On 26.07.2011 05:45, cerr wrote:
>
>
>
> > I'm just trying to write a little sample program with a thread. I can't get my thread started and am not sure why, I get
> > $ g++ -o example example.cpp
> > example.cpp: In member function ‘int MyThread::StartMe()’:
> > example.cpp:42:59: error: expected primary-expression before ‘void’
> > example.cpp:42:63: error: initializer expression list treated as compound expression
> > the code:
> > int MyThread::StartMe(void)
> > {
> >    int pthread_create(&ThreadA, NULL,&MyThread::PrintMsg, void);
>
> `void` is a type.

Hi Alf, yep I've figured that out by now but passing NULL doesn't work
either, how do I pass a void argument when my thread function is
declared like:  void PrintMsg(void);?
Thanks!

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#8235

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!

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#8237

On 07/26/11 06:53 PM, cerr wrote:
> 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!

Pass the the correct function type!

extern "C" void* PrintMsg(void*)

-- 
Ian Collins

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#8238

"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);
}

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#8239

"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);
}

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#8243

"io_x" <a@b.c.invalid> ha scritto nel messaggio
news:4e2e7ad0$0$15664$4fafbaef@reader2.news.tin.it...

what do you think about this?
It is a good way for threads?

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

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

#define   ini     InitializeCriticalSection
#define   lock    EnterCriticalSection
#define   unlock  LeaveCriticalSection
#define   end     DeleteCriticalSection
#define   P       printf

CRITICAL_SECTION  dataTh;

int  hhh;

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

 aa=*(unsigned*)a;
  while(count<=100)
  {lock( &dataTh );
   count++;
   if(count<=100)
      {cout << "Tread number=" << aa << ";  ";
       cout << "I Incremented count: " << count << "\n";
      }
   else  {++hhh; P("wait 10sec hhh=%d\r", hhh);}
   unlock( &dataTh );
  }

 return 0;
}

unsigned StartMe(int  i)
{// starting thread
 unsigned long  id=0;
 void       *hThread;


 ++index; index&=255; array[index]=i;
 hThread=CreateThread(0, 0, PrintMsg, array+index, 0, &id);
 if(hThread == 0 ) return -1;
 return 0;
}

int main(void)
{int i;

 ini(&dataTh);

 for(i=0; i<100; ++i)
       if((int)StartMe(i)==-1)  break;

 Sleep(10000); // 10 secondi

 end(&dataTh);
 printf("\n");
 return 0;
}



Tread number=0;  I Incremented count: 1
Tread number=1;  I Incremented count: 2
Tread number=3;  I Incremented count: 3
Tread number=5;  I Incremented count: 4
Tread number=2;  I Incremented count: 5
Tread number=7;  I Incremented count: 6
Tread number=9;  I Incremented count: 7
Tread number=11;  I Incremented count: 8
Tread number=13;  I Incremented count: 9
Tread number=4;  I Incremented count: 10
Tread number=6;  I Incremented count: 11
Tread number=8;  I Incremented count: 12
Tread number=15;  I Incremented count: 13
Tread number=10;  I Incremented count: 14
Tread number=12;  I Incremented count: 15
Tread number=17;  I Incremented count: 16
Tread number=19;  I Incremented count: 17
Tread number=21;  I Incremented count: 18
Tread number=14;  I Incremented count: 19
Tread number=16;  I Incremented count: 20
Tread number=0;  I Incremented count: 21
Tread number=24;  I Incremented count: 22
Tread number=23;  I Incremented count: 23
Tread number=25;  I Incremented count: 24
Tread number=27;  I Incremented count: 25
Tread number=29;  I Incremented count: 26
Tread number=22;  I Incremented count: 27
Tread number=20;  I Incremented count: 28
Tread number=18;  I Incremented count: 29
Tread number=31;  I Incremented count: 30
Tread number=26;  I Incremented count: 31
Tread number=33;  I Incremented count: 32
Tread number=28;  I Incremented count: 33
Tread number=35;  I Incremented count: 34
Tread number=30;  I Incremented count: 35
Tread number=37;  I Incremented count: 36
Tread number=39;  I Incremented count: 37
Tread number=1;  I Incremented count: 38
Tread number=41;  I Incremented count: 39
Tread number=43;  I Incremented count: 40
Tread number=45;  I Incremented count: 41
Tread number=32;  I Incremented count: 42
Tread number=34;  I Incremented count: 43
Tread number=36;  I Incremented count: 44
Tread number=47;  I Incremented count: 45
Tread number=49;  I Incremented count: 46
Tread number=38;  I Incremented count: 47
Tread number=40;  I Incremented count: 48
Tread number=51;  I Incremented count: 49
Tread number=53;  I Incremented count: 50
Tread number=42;  I Incremented count: 51
Tread number=55;  I Incremented count: 52
Tread number=44;  I Incremented count: 53
Tread number=59;  I Incremented count: 54
Tread number=57;  I Incremented count: 55
Tread number=46;  I Incremented count: 56
Tread number=48;  I Incremented count: 57
Tread number=63;  I Incremented count: 58
Tread number=61;  I Incremented count: 59
Tread number=50;  I Incremented count: 60
Tread number=3;  I Incremented count: 61
Tread number=65;  I Incremented count: 62
Tread number=66;  I Incremented count: 63
Tread number=67;  I Incremented count: 64
Tread number=64;  I Incremented count: 65
Tread number=69;  I Incremented count: 66
Tread number=62;  I Incremented count: 67
Tread number=60;  I Incremented count: 68
Tread number=58;  I Incremented count: 69
Tread number=56;  I Incremented count: 70
Tread number=54;  I Incremented count: 71
Tread number=52;  I Incremented count: 72
Tread number=71;  I Incremented count: 73
Tread number=73;  I Incremented count: 74
Tread number=75;  I Incremented count: 75
Tread number=68;  I Incremented count: 76
Tread number=77;  I Incremented count: 77
Tread number=79;  I Incremented count: 78
Tread number=70;  I Incremented count: 79
Tread number=72;  I Incremented count: 80
Tread number=81;  I Incremented count: 81
Tread number=76;  I Incremented count: 82
Tread number=5;  I Incremented count: 83
Tread number=74;  I Incremented count: 84
Tread number=83;  I Incremented count: 85
Tread number=87;  I Incremented count: 86
Tread number=89;  I Incremented count: 87
Tread number=91;  I Incremented count: 88
Tread number=93;  I Incremented count: 89
Tread number=95;  I Incremented count: 90
Tread number=85;  I Incremented count: 91
Tread number=97;  I Incremented count: 92
Tread number=78;  I Incremented count: 93
Tread number=99;  I Incremented count: 94
Tread number=80;  I Incremented count: 95
Tread number=82;  I Incremented count: 96
Tread number=84;  I Incremented count: 97
Tread number=86;  I Incremented count: 98
Tread number=88;  I Incremented count: 99
Tread number=90;  I Incremented count: 100
wait 10sec hhh=100

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#8244

On 07/26/11 10:38 PM, io_x wrote:
> "io_x"<a@b.c.invalid>  ha scritto nel messaggio
> news:4e2e7ad0$0$15664$4fafbaef@reader2.news.tin.it...
>
> what do you think about this?
> It is a good way for threads?
>
> #include<stdio.h>
> #include<iostream.h>
> #include<windows.h>
>
> unsigned  count=0;
> unsigned  index=-1;
> unsigned  array[256];
>
> #define   ini     InitializeCriticalSection

NO!

-- 
Ian Collins

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#8245

On 07/26/11 07:57 PM, io_x wrote:
> -------------------
> i modify somthing; in printmsg i impose count<100000
>
> unsigned  count=0;
>
> void* PrintMsg(void*  unused)

A C library expects a C linkage function pointer, so give it one.

> {(void) unused;

You don't need the awful Cism in C++, just leave the parameter unnamed.

-- 
Ian Collins

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