C++获取当前系统时间

首先，包含如下头文件：

#include "sys/time.h"
#include 

实现函数，分不同平台：

double Common::getTime() {
#ifdef _WIN32
    FILETIME ft;
    double t;
    GetSystemTimeAsFileTime(&ft);
    /* Windows file time (time since January 1, 1601 (UTC)) */
    t  = ft.dwLowDateTime/1.0e7 + ft.dwHighDateTime*(4294967296.0/1.0e7);
    /* convert to Unix Epoch time (time since January 1, 1970 (UTC)) */
    return (t - 11644473600.0);
#else
    struct timeval v;
    gettimeofday(&v, (struct timezone *) NULL);
    /* Unix Epoch time (time since January 1, 1970 (UTC)) */
    return v.tv_sec + v.tv_usec/1.0e6;
#endif
}