CreateThread Function

HANDLE CreateThread(
  LPSECURITY_ATTRIBUTES lpThreadAttributes,
  SIZE_T dwStackSize,
  LPTHREAD_START_ROUTINE lpStartAddress,
  LPVOID lpParameter,
  DWORD dwCreationFlags,
  LPDWORD lpThreadId
);

Parameters

Parameter	Description
lpThreadAttributes	A pointer to a SECURITY_ATTRIBUTES structure that specifies the security attributes of the new thread. If this parameter is NULL, the thread gets a default security descriptor, and the new thread inherits its creator's process-handle access-control list (ACL).
dwStackSize	The initial region size, in bytes, of the stack allocated for the new thread. If this parameter is 0, the server allocates a stack of the same size as that used by the calling thread of the process.
lpStartAddress	A pointer to the application-defined function of type LPTHREAD_START_ROUTINE that the thread should execute. This is a pointer to the beginning of the routine.
lpParameter	A pointer to a variable to be passed to the thread function.
dwCreationFlags	Flags that control the thread's creation. 0: The thread runs immediately after creation. CREATE_SUSPENDED: The thread is created in a suspended state. Use ResumeThread to begin execution.
lpThreadId	A pointer to a 32-bit variable that receives the thread identifier of the new thread. If this parameter is NULL, the thread identifier is not returned.

Return Value

If the function succeeds, the return value is a handle to the new thread. If the function fails, the return value is NULL. To get extended error information, call GetLastError.

Remarks

The thread runs in the address space of the calling process and uses the process's handle table. The thread continues executing until it calls the ExitThread function, the from-process thread of execution returns from the thread function, or the process terminates.

Example

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

// Thread function
DWORD WINAPI MyThreadFunction(LPVOID lpParam) {
    int threadNum = *(int*)lpParam;
    std::wcout << L"Hello from thread " << threadNum << L"!" << std::endl;
    return 0;
}

int main() {
    HANDLE hThread;
    DWORD threadID;
    int threadNum = 1;

    // Create the thread
    hThread = CreateThread(
        NULL,       // Default security attributes
        0,          // Default stack size
        MyThreadFunction, // Thread function
        &threadNum, // Parameter to thread function
        0,          // Run immediately
        &threadID); // Returns the thread identifier

    if (hThread == NULL) {
        std::cerr << "Failed to create thread. Error: " << GetLastError() << std::endl;
        return 1;
    }

    std::wcout << L"Thread created successfully with ID: " << threadID << std::endl;

    // Wait for the thread to finish
    WaitForSingleObject(hThread, INFINITE);

    // Close the thread handle
    CloseHandle(hThread);

    std::wcout << L"Main thread exiting." << std::endl;

    return 0;
}