times(NULL) Segmentation fault

******************************************************************************
 *                   times(NULL) Segmentation fault
 * 说明：
 *     在PC机上times(NULL)是没问题的，但在嵌入式Linux上，貌似不传递参数是有可能
 * 会出问题的。
 *
 *                                         2017-7-6 深圳 龙华樟坑村 曾剑锋
 *****************************************************************************/

一、参考文档：
    . Segmentation fault using ctime
        https://stackoverflow.com/questions/12338947/segmentation-fault-using-ctime
    . Segmentation fault on time();
        https://stackoverflow.com/questions/1731802/segmentation-fault-on-time0
    . segmentation fault (core dumped) error when using time function
        https://stackoverflow.com/questions/20939415/segmentation-fault-core-dumped-error-when-using-time-function
　　 4. An application encounters segmentation fault in glibc's times(2) function
　　　　 https://access.redhat.com/solutions/1124633

二、测试代码：
    #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()
        {
            // unsigned long tick = times(NULL);    // don't use this. it may cause segmentation fault.
            unsigned long tick = times(&tmp);
            unsigned long RetUl = ( / SysF) * tick;

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

            usleep();
        }

        return ;
    }