1、线程是附属在进程上的执行实体，是代码的执行流程。

2、一个进程可以包含多个线程，但一个进程至少要包含一个线程。

进程是空间的概念，挂起进程，实际上是挂起线程；线程是时间概念，线程有多少个，说明有多少个代码段在执行。如何理解多个代码段在执行？

- 单核状态下，线程交叉执行，感觉上是同时执行的；
- 多核状态下，多尔CPU同时执行。

创建线程

```c++
HANDLE CreateThread(
	lpSECURITY_ATTBUTES lpThreadAttributes, //SD 只要是内核对象都会有SD安全描述符
    SIZE_T dwStackSize, //初始化堆栈大小
    LPTHREAD_START_ROUTINE lpStartAddress, //线程执行的函数地址
    LPVOID lpParameter, //线程执行的函数参数
    DWORD dwCreationFlags, //创建选项
    LPDWORD lpThreadId //输出 线程标识符
)
```

无参数创建线程

```c++
#include "stdafx.h"
#include <windows.h>
//线程函数
VOID __stdcall testProc()
{
    for(int i=100; i>0; i--)
    {
        Sleep(500);
        printf("+++++++ %d\n", i);
    }
}
//外平栈
DWORD WINAPI ThreadProc(LPVOID lpParameter)
{
    for(int i=100; i>0; i--)
    {
        Sleep(500);
        printf("++++++++ %d\n", i);
    }
    return 0L;
}
int _tmain(int argc, _TCHAR* argv[])
{
    HANDLE hThread;
    hThread = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)testProc, NULL, 0, NULL);
    CloseHandle(hThread);
    for(int i=100; i>0; i--)
    {
        Sleep(500);
        printf("--------%d\n", i);
    }
    return 0;
}
```


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