Cast std::thread as HANDLE to call TerminateThread() [duplicate] - c++

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How to get the winapi id of a thread that has been created using the standard library?
(2 answers)
Closed 7 years ago.
Could it be posible to cast or convert a std::thread thread in C++ to a HANDLE in Windows?
I've been trying to manage threads in Windows with WINAPI functions for threads but I can't get it to work...
#include <thread>
#include <string>
#include <iostream>
#include <windows.h>
void Hi(std::string n){
while(true){
std::cout<<"Hi :3 "<<n<<"\n";
std::this_thread::sleep_for(std::chrono::seconds(1));
}
}
int main(void){
std::thread first(Hi, "zoditu");
first.detach();
getc(stdin);
//SuspendThread((void*)first.native_handle());
TerminateThread((void*)first.native_handle(), (unsigned long)0x00);
CloseHandle((void*)first.native_handle());
std::cout<<"No D:!!\n";
getc(stdin);
return 0;
}
But seems to do nothing because thread keeps spawning "Hi's" in the console... Could there be a way to "kill" it using WINAPI?

Answer 1

I don't think there is anything wrong with using the value returned by std::thread::native_handle() directly with the Win32 API functions (i.e., a conversion is not required).
The following program works for me. However, it usually (always?) crashes if the thread is terminated while it is actively executing but works just fine if the thread is suspended before terminating. As you are aware and others have pointed out it is generally not a good idea to terminate a thread.
But to answer your question the Win32 API seems to work as expected without any additional conversions. The following program works for me.
Program:
#include <windows.h>
#include <iostream>
#include <string>
#include <thread>
void foo()
{
while (true)
{
std::cout << "foo()\n";
std::this_thread::sleep_for(std::chrono::seconds(1));
}
}
int main(void)
{
std::thread first(foo);
bool isFinished = false;
while (!isFinished)
{
char ch = ::getchar();
::getchar(); // Swallow the new line character
if (ch == 'e')
{
isFinished = true;
}
else if (ch == 's')
{
DWORD result = ::SuspendThread(first.native_handle());
if (result != -1)
{
std::cout << "Successfully suspended thread\n";
}
else
{
std::cout << "Failed to suspend thread: failure resson " << ::GetLastError() << "\n";
}
}
else if (ch == 'r')
{
DWORD result = ::ResumeThread(first.native_handle());
if (result != -1)
{
std::cout << "Successfully resumed thread\n";
}
else
{
std::cout << "Failed to resume thread: failure resson " << ::GetLastError() << "\n";
}
}
else if (ch == 'k')
{
DWORD result = ::TerminateThread(first.native_handle(), 1);
if (result != 0)
{
std::cout << "Successfully terminated thread\n";
}
else
{
std::cout << "Failed to terminate thread: failure resson " << ::GetLastError() << "\n";
}
}
else
{
std::cout << "Unhandled char '" << ch << "'\n";
}
}
first.detach();
std::cout << "waiting to exit main...";
::getchar();
std::cout << "exiting...\n";
return 0;
}
Sample Output (comments added by me):
foo()
foo()
foo()
foo()
s
Successfully suspended thread // This was successful since 'foo()' is no longer printing
r
Successfully resumed thread // This was successful since 'foo()' is again printing
foo()
foo()
foo()
foo()
s
Successfully suspended thread // Worked again
k
Successfully terminated thread // Says it works...
r
Successfully resumed thread // Termination must have worked because resuming did not cause 'foo' to start printing
e
waiting to exit main...
exiting...