Не понимаю как работает многопоточность

Не понимаю, как синхронизировать потоки и вообще их юзать. Использовать PIPE нужно обязательно. Вроде все по докам сделал, а как заставить заработать не понимаю. Чат гпт и прочая нечесть не помогают...

#include <iostream>
#include <Windows.h>
#include <math.h>

const char* PIPE = "\\\\.\\pipe\\hypotenuse_pipe";
CRITICAL_SECTION cs_finished;
volatile bool finished = false;


DWORD WINAPI square_thread(LPVOID param)
{
HANDLE hPipeRead = CreateFile(PIPE, GENERIC_READ, 0, NULL, OPEN_EXISTING, 0, NULL);
HANDLE hPipeWrite = CreateFile(PIPE, GENERIC_WRITE, 0, NULL, OPEN_EXISTING, 0, NULL);
if (hPipeRead == INVALID_HANDLE_VALUE || hPipeWrite == INVALID_HANDLE_VALUE)
{
return 1;
}

double value;
DWORD bytesRead, bytesWritten;
for (int i = 0; i < 2; ++i)
{
EnterCriticalSection(&cs_finished);
if (finished)
{
LeaveCriticalSection(&cs_finished);
break;
}
LeaveCriticalSection(&cs_finished);

if (ReadFile(hPipeRead, &value, sizeof(double), &bytesRead, NULL) &&
bytesRead == sizeof(double))
{
double result = value * value;
WriteFile(hPipeWrite, &result, sizeof(double), &bytesWritten, NULL);
}
}

CloseHandle(hPipeRead);
CloseHandle(hPipeWrite);
return 0;
}



DWORD WINAPI sum_thread(LPVOID param)
{
HANDLE hPipeRead = CreateFile(PIPE, GENERIC_READ, 0, NULL, OPEN_EXISTING, 0, NULL);
HANDLE hPipeWrite = CreateFile(PIPE, GENERIC_WRITE, 0, NULL, OPEN_EXISTING, 0, NULL);
if (hPipeRead == INVALID_HANDLE_VALUE || hPipeWrite == INVALID_HANDLE_VALUE)
{
return 1;
}

EnterCriticalSection(&cs_finished);
if (finished)
{
LeaveCriticalSection(&cs_finished);
CloseHandle(hPipeRead);
CloseHandle(hPipeWrite);
return 0;
}
LeaveCriticalSection(&cs_finished);

double value1, value2;
DWORD bytesRead, bytesWritten;
if (ReadFile(hPipeRead, &value1, sizeof(double), &bytesRead, NULL) &&
bytesRead == sizeof(double) &&
ReadFile(hPipeRead, &value2, sizeof(double), &bytesRead, NULL) &&
bytesRead == sizeof(double))
{
double result = value1 + value2;
WriteFile(hPipeWrite, &result, sizeof(double), &bytesWritten, NULL);
}

CloseHandle(hPipeRead);
CloseHandle(hPipeWrite);
return 0;
}


DWORD WINAPI sqrt_thread(LPVOID param)
{
HANDLE hPipeRead = CreateFile(PIPE, GENERIC_READ, 0, NULL, OPEN_EXISTING, 0, NULL);
HANDLE hPipeWrite = CreateFile(PIPE, GENERIC_WRITE, 0, NULL, OPEN_EXISTING, 0, NULL);
if (hPipeRead == INVALID_HANDLE_VALUE || hPipeWrite == INVALID_HANDLE_VALUE)
{
return 1;
}

EnterCriticalSection(&cs_finished);
if (finished)
{
LeaveCriticalSection(&cs_finished);
CloseHandle(hPipeRead);
CloseHandle(hPipeWrite);
return 0;
}
LeaveCriticalSection(&cs_finished);

double value;
DWORD bytesRead, bytesWritten;
if (ReadFile(hPipeRead, &value, sizeof(double), &bytesRead, NULL)
&& bytesRead == sizeof(double))
{
double result = sqrt(value);
WriteFile(hPipeWrite, &result, sizeof(double), &bytesWritten, NULL);
}

CloseHandle(hPipeRead);
CloseHandle(hPipeWrite);
return 0;
}


int main()
{
InitializeCriticalSection(&cs_finished);

HANDLE hPipe = CreateNamedPipe(
PIPE,
PIPE_ACCESS_DUPLEX,
PIPE_TYPE_MESSAGE | PIPE_READMODE_MESSAGE | PIPE_WAIT,
PIPE_UNLIMITED_INSTANCES,
4096,
4096,
0,
NULL
);

if (hPipe == INVALID_HANDLE_VALUE)
{
return 1;
}

DWORD t1, t2, t3;
HANDLE h1 = CreateThread(NULL, 0, square_thread, NULL, 0, &t1);
HANDLE h2 = CreateThread(NULL, 0, sum_thread, NULL, 0, &t2);
HANDLE h3 = CreateThread(NULL, 0, sqrt_thread, NULL, 0, &t3);


if (!ConnectNamedPipe(hPipe, NULL) && GetLastError() != ERROR_PIPE_CONNECTED)
{
CloseHandle(hPipe);
return 1;
}
double a, b;
std::cout << "Enter a = ";
std::cin >> a;
std::cout << "Enter b = ";
std::cin >> b;


DWORD bytesWritten;
WriteFile(hPipe, &a, sizeof(double), &bytesWritten, NULL);
WriteFile(hPipe, &b, sizeof(double), &bytesWritten, NULL);

double result;
DWORD bytesRead;
if (ReadFile(hPipe, &result, sizeof(double), &bytesRead, NULL) && bytesRead == sizeof(double))
{
std::cout << "result = " << result << std::endl;
}

EnterCriticalSection(&cs_finished);
finished = true;
LeaveCriticalSection(&cs_finished);

WaitForSingleObject(h1, INFINITE);
WaitForSingleObject(h2, INFINITE);
WaitForSingleObject(h3, INFINITE);

CloseHandle(h1);
CloseHandle(h2);
CloseHandle(h3);
CloseHandle(hPipe);
DeleteCriticalSection(&cs_finished);

return 0;
}

C

#include <iostream>

#include <Windows.h>

#include <math.h>



const char* PIPE = "\\\\.\\pipe\\hypotenuse_pipe";

CRITICAL_SECTION cs_finished;

volatile bool finished = false;





DWORD WINAPI square_thread(LPVOID param)

{

    HANDLE hPipeRead = CreateFile(PIPE, GENERIC_READ, 0, NULL, OPEN_EXISTING, 0, NULL);

    HANDLE hPipeWrite = CreateFile(PIPE, GENERIC_WRITE, 0, NULL, OPEN_EXISTING, 0, NULL);

    if (hPipeRead == INVALID_HANDLE_VALUE || hPipeWrite == INVALID_HANDLE_VALUE)

    {

        return 1;

    }



    double value;

    DWORD bytesRead, bytesWritten;

    for (int i = 0; i < 2; ++i)

    {

        EnterCriticalSection(&cs_finished);

        if (finished)

        {

            LeaveCriticalSection(&cs_finished);

            break;

        }

        LeaveCriticalSection(&cs_finished);



        if (ReadFile(hPipeRead, &value, sizeof(double), &bytesRead, NULL) &&

        bytesRead == sizeof(double))

        {

            double result = value * value;

            WriteFile(hPipeWrite, &result, sizeof(double), &bytesWritten, NULL);

        }

    }



    CloseHandle(hPipeRead);

    CloseHandle(hPipeWrite);

    return 0;

}







DWORD WINAPI sum_thread(LPVOID param)

{

    HANDLE hPipeRead = CreateFile(PIPE, GENERIC_READ, 0, NULL, OPEN_EXISTING, 0, NULL);

    HANDLE hPipeWrite = CreateFile(PIPE, GENERIC_WRITE, 0, NULL, OPEN_EXISTING, 0, NULL);

    if (hPipeRead == INVALID_HANDLE_VALUE || hPipeWrite == INVALID_HANDLE_VALUE)

    {

        return 1;

    }



    EnterCriticalSection(&cs_finished);

    if (finished)

    {

        LeaveCriticalSection(&cs_finished);

        CloseHandle(hPipeRead);

        CloseHandle(hPipeWrite);

        return 0;

    }

    LeaveCriticalSection(&cs_finished);



    double value1, value2;

    DWORD bytesRead, bytesWritten;

    if (ReadFile(hPipeRead, &value1, sizeof(double), &bytesRead, NULL) &&

    bytesRead == sizeof(double) &&

    ReadFile(hPipeRead, &value2, sizeof(double), &bytesRead, NULL) &&

        bytesRead == sizeof(double))

    {

        double result = value1 + value2;

        WriteFile(hPipeWrite, &result, sizeof(double), &bytesWritten, NULL);

    }



    CloseHandle(hPipeRead);

    CloseHandle(hPipeWrite);

    return 0;

}





DWORD WINAPI sqrt_thread(LPVOID param)

{

    HANDLE hPipeRead = CreateFile(PIPE, GENERIC_READ, 0, NULL, OPEN_EXISTING, 0, NULL);

    HANDLE hPipeWrite = CreateFile(PIPE, GENERIC_WRITE, 0, NULL, OPEN_EXISTING, 0, NULL);

    if (hPipeRead == INVALID_HANDLE_VALUE || hPipeWrite == INVALID_HANDLE_VALUE)

    {

        return 1;

    }



    EnterCriticalSection(&cs_finished);

    if (finished)

    {

        LeaveCriticalSection(&cs_finished);

        CloseHandle(hPipeRead);

        CloseHandle(hPipeWrite);

        return 0;

    }

    LeaveCriticalSection(&cs_finished);



    double value;

    DWORD bytesRead, bytesWritten;

    if (ReadFile(hPipeRead, &value, sizeof(double), &bytesRead, NULL)

    && bytesRead == sizeof(double))

    {

        double result = sqrt(value);

        WriteFile(hPipeWrite, &result, sizeof(double), &bytesWritten, NULL);

    }



    CloseHandle(hPipeRead);

    CloseHandle(hPipeWrite);

    return 0;

}





int main()

{

    InitializeCriticalSection(&cs_finished);



    HANDLE hPipe = CreateNamedPipe(

        PIPE,

        PIPE_ACCESS_DUPLEX,

        PIPE_TYPE_MESSAGE | PIPE_READMODE_MESSAGE | PIPE_WAIT,

        PIPE_UNLIMITED_INSTANCES,

        4096,

        4096,

        0,

        NULL

    );



    if (hPipe == INVALID_HANDLE_VALUE)

    {

        return 1;

    }



    DWORD t1, t2, t3;

    HANDLE h1 = CreateThread(NULL, 0, square_thread, NULL, 0, &t1);

    HANDLE h2 = CreateThread(NULL, 0, sum_thread, NULL, 0, &t2);

    HANDLE h3 = CreateThread(NULL, 0, sqrt_thread, NULL, 0, &t3);





    if (!ConnectNamedPipe(hPipe, NULL) && GetLastError() != ERROR_PIPE_CONNECTED)

    {

        CloseHandle(hPipe);

        return 1;

    }

    double a, b;

    std::cout << "Enter a = ";

    std::cin >> a;

    std::cout << "Enter b = ";

    std::cin >> b;





    DWORD bytesWritten;

    WriteFile(hPipe, &a, sizeof(double), &bytesWritten, NULL);

    WriteFile(hPipe, &b, sizeof(double), &bytesWritten, NULL);



    double result;

    DWORD bytesRead;

    if (ReadFile(hPipe, &result, sizeof(double), &bytesRead, NULL) && bytesRead == sizeof(double))

    {

        std::cout << "result = " << result << std::endl;

    }



    EnterCriticalSection(&cs_finished);

    finished = true;

    LeaveCriticalSection(&cs_finished);



    WaitForSingleObject(h1, INFINITE);

    WaitForSingleObject(h2, INFINITE);

    WaitForSingleObject(h3, INFINITE);



    CloseHandle(h1);

    CloseHandle(h2);

    CloseHandle(h3);

    CloseHandle(hPipe);

    DeleteCriticalSection(&cs_finished);



    return 0;

}