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