C\C++下获取系统进程或线程ID

在程序开发时有时需要获取线程和进程ID以分析程序运行
(1)windows下获取进程或线程ID
通过调用系统提供的GetCurProcessId或GetNowThreadID来获取当前程序代码运行时的进程或线程ID
示例代码：

#include "windows.h"
printf("now pid is %d", GetCurrentProcessId());
printf("now tid is %d", GetCurrentThreadId());

(2)linux下获取进程或线程ID
通过getpid和gettid获取进程或线程ID
示例代码：

#include "unistd.h"
printf("now pid is %d \n", getpid());
printf("now tid is %d \n", gettid());

(3)跨平台设计
为了便于跨平台开发，可利用宏定义支持代码跨平台
示例代码

#ifndef __linux__
#include "windows.h"
#else
#include "unistd.h"
#endif

#ifndef __linux__
printf("now pid is %d \n", GetCurrentProcessId());
printf("now tid is %d \n", GetCurrentThreadId());

#else
printf("now pid is %d \n", getpid());
printf("now tid is %d \n", gettid());
#endif