/******************************************************************************
 *                   times(NULL) Segmentation fault
 * 說明：
 *     在PC機上times(NULL)是沒問題的，但在嵌入式Linux上，貌似不傳遞參數是有可能
 * 會出問題的。
 *
 *                                         2017-7-6 深圳 龍華樟坑村 曾劍鋒
 ****************************************************************************
 
*/

一、參考文檔：
    1. Segmentation fault using ctime
        https://stackoverflow.com/questions/12338947/segmentation-fault-using-ctime    
    2. Segmentation fault on time(0);
        https://stackoverflow.com/questions/1731802/segmentation-fault-on-time0
    3. segmentation fault (core dumped) error when using
 
 time function
        https://stackoverflow.com/questions/20939415/segmentation-fault-core-dumped-error-when-using-time-function

二、測試代碼：
    #include <iostream>
    #include <sys/times.h>
    #include <unistd.h>

    using namespace std;

    int main()
    {
        unsigned 
 
long SysF = sysconf(_SC_CLK_TCK);
        struct tms tmp;

        while(1)
        {
            // unsigned long tick = times(NULL);    // don‘t use this. it may cause segmentation fault.
            unsigned long tick = times(&tmp);
            unsigned long RetUl = (1000 / SysF) * tick;

            cout << "tick: " << tick << " RetUl: " << RetUl << endl;

            usleep(10000);
        }

        return 0;
    }

times(NULL) Segmentation fault