CreateThread function

Header: processthreadsapi.h

Library: Kernel32.lib

Syntax

#include <windows.h>

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

Parameters

Name	Type	Description
lpThreadAttributes	LPSECURITY_ATTRIBUTES	Pointer to a SECURITY_ATTRIBUTES structure or `NULL` for default.
dwStackSize	SIZE_T	Initial stack size, in bytes. `0` uses the default size.
lpStartAddress	LPTHREAD_START_ROUTINE	Pointer to the application-defined function to be executed by the thread.
lpParameter	LPVOID	Single argument passed to the thread function.
dwCreationFlags	DWORD	Flags that control the creation of the thread. Use `0` for immediate start or `CREATE_SUSPENDED` to start suspended.
lpThreadId	LPDWORD	Pointer to a variable that receives the thread identifier. May be `NULL`.

Return value

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

Remarks

The thread created by CreateThread runs in the same process as the calling thread.
Close the thread handle with CloseHandle when it is no longer needed.
For managed code or when using the Common Language Runtime, prefer CreateThread over _beginthreadex only when you do not need the CRT's thread initialization.
Use CREATE_SUSPENDED and ResumeThread to control start order.

Example

#include <windows.h>
#include <stdio.h>

DWORD WINAPI MyThreadFunction(LPVOID lpParam) {
    int *pVal = (int*)lpParam;
    printf("Thread %d running, received value %d\\n", GetCurrentThreadId(), *pVal);
    return 0;
}

int main(void) {
    int value = 42;
    HANDLE hThread = CreateThread(
        NULL,               // default security attributes
        0,                  // default stack size
        MyThreadFunction,   // thread function
        &value,             // argument to thread function
        0,                  // default creation flags
        NULL);              // ignore thread identifier

    if (hThread == NULL) {
        printf("CreateThread failed (%lu)\\n", GetLastError());
        return 1;
    }

    WaitForSingleObject(hThread, INFINITE);
    CloseHandle(hThread);
    return 0;
}

Microsoft Docs