FAQ: How to do simple multi-threading in C/C++? (C++)

[sbasak]

Hi Everyone

I like to know how I can implement multi-threading in C/C++ programs.

Is it possible to do multi-threading with only one processor?

Can you please show me a SIMPLE C/C++ program which performs multi-threading?

I am using Visual C++ 5 compiler.

Thanks a lot :-)

[btq]

something like this:

DWORD WINAPI ThreadFunc( LPVOID lpParam )  
{ 
    char szMsg[80];

    wsprintf( szMsg, "ThreadFunc: Parameter = %d\n", *lpParam ); 
    MessageBox( NULL, szMsg, "Thread created.", MB_OK );

    return 0; 
} 
 
VOID main( VOID ) 
{ 
    DWORD dwThreadId, dwThrdParam = 1; 
    HANDLE hThread; 
    hThread = CreateThread( 
        NULL,                        // no security attributes 
        0,                           // use default stack size  
        ThreadFunc,                  // thread function 

        &dwThrdParam,                // argument to thread function 
        0,                           // use default creation flags 
        &dwThreadId);                // returns the thread identifier 
 
   // Check the return value for success. 
 
   if (hThread == NULL) 
      ErrorExit( "CreateThread failed." ); 

   CloseHandle( hThread );
}

from the win32.hlp..
and please do notice the VOID main()

/btq

[sbasak]

what files to include, it's giving error even after #include<windows.h>

why VOID anyway? how it differs from void?

[btq]

you should have
#include <windows.h>
#include <conio.h>
in there, sorry bout that..

/btq

[sbasak]

In Visual C++ 5 it says

illegal indirection in line wsprintf( szMsg, "ThreadFunc: Parameter = %d\n", *lpParam );

and

ErrorExit -> undeclared identifier

[btq]

well,for simplicity,just get rid of them then, it's not as if they are the ones makin
the threadin here

just do somethin like:
MessageBox( NULL, "hi I'm the thread", "Thread created.", MB_OK ); instead and exchange the Error-thingie with
MessageBox( NULL, "something wrong with the hThread man!", "error.", MB_OK );

see if that works..
/btq

[sbasak]

now it says linking error

unresolved external symbol _WinMain@16