C++ CreateThread() strange error

Question

I try to use CreateThread() function in my application, but I get strange error, exactly:

error: invalid conversion from 'DWORD (__ attribute__((__ stdcall__)) *)() {aka long unsigned int (__ attribute__((__ stdcall__)) *)()}' to 'LPTHREAD_START_ROUTINE {aka long unsigned int (__ attribute__((__ stdcall__)) *)(void*)}' [-fpermissive]

and

In file included from c:\program files (x86)\codeblocks\mingw\bin\../lib/gcc/mingw32/4.7.1/../../../../include/windows.h:50:0,

             from c:\program files (x86)\codeblocks\mingw\bin\../lib/gcc/mingw32/4.7.1/../../../../include/winsock2.h:22,
             from c:\program files (x86)\codeblocks\mingw\bin\../lib/gcc/mingw32/4.7.1/../../../../include/ws2tcpip.h:19,
             from include/WinSockClass.hpp:3,
             from C:\Users\Jakub\Desktop\offline\Server\main.cpp:15:
c:\program files (x86)\codeblocks\mingw\bin\../lib/gcc/mingw32/4.7.1/../../../../include/winbase.h:1423:26: error:   initializing argument 3 of 'void* CreateThread(LPSECURITY_ATTRIBUTES, DWORD, LPTHREAD_START_ROUTINE, PVOID, DWORD, PDWORD)' [-fpermissive]

second indicates line

WINBASEAPI HANDLE WINAPI CreateThread(LPSECURITY_ATTRIBUTES,DWORD,LPTHREAD_START_ROUTINE,PVOID,DWORD,PDWORD);

in winbase.h, I don't understand what going on, in examples is same thing, but without error. What I do wrong ?

code:

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

using namespace std;

int a()
{
   cout << "work";
   return 0;
}
int main(int argc, char **argv)
{
    CreateThread(NULL,0,a,NULL,0,NULL);
    return 0;
}

The error message says exactly what is wrong. You passed the wrong type of function pointer. The error message says both what you passed and what you were supposed to pass. — Raymond Chen, Feb 27 '16 at 21:02
The thread function *must* be defined correctly. See [the documentation](https://msdn.microsoft.com/en-us/library/windows/desktop/ms686736(v=vs.85).aspx). — Harry Johnston, Feb 27 '16 at 21:18

score 0 · Answer 1 · answered Feb 27 '16 at 21:23

OK, is my fault, that works

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

using namespace std;

DWORD WINAPI a(LPVOID lpParameter)
{
   cout << "work";
   return 0;
}
int main(int argc, char **argv)
{
    CreateThread(NULL,0,a,NULL,0,NULL);
    return 0;
}

C++ CreateThread() strange error

1 Answers1