常用的时间类型转换

 在程序开发过程中不断会碰到不同的数据间的转换,在这里做一个总结:
一.时间类型间的转换:
1.time_t 转  FILETIME
 FILETIME ft;
 LONGLONG ll = Int32x32To64(t, 10000000) + 116444736000000000;
 ft.dwLowDateTime = (DWORD) ll;

 ft.dwHighDateTime = (DWORD)(ll >> 32);

2.FILETIME 转 time_t  
FILETIME ft;
time_t t;
LONGLONG llTime = ft.dwHighDateTime;
llTime <<= 32;
llTime |= ft.dwLowDateTime;
t = (DWORD)((LONGLONG)(llTime - 116444736000000000) / 10000000);

3.SYSTEMTIME 转 FILETIME
FILETIME ft;
SYSTEMTIME st;
SystemTimeToFileTime( &st, &ft );

4. FILETIME 转 SYSTEMTIME
FILETIME ft;
SYSTEMTIME st;
FileTimeToSystemTime( &ft, &st);

5.DATE 转 SYSTEMTIME
DATE pst;
SYSTEMTIME st;
VariantTimeToSystemTime(pst,&st);

6. SYSTEMTIME 转 DATE 
DATE pst;
SYSTEMTIME st;

SystemTimeToVariantTime(st, &pst);

7. BYTE转DWORD

 #define   MAKEB2W(c0, c1, c2, c3) ((DWORD)(((BYTE)(c0)|((WORD)((BYTE)(c1))<<8))|(((DWORD)(BYTE)(c2))<<16) | (((DWORD)(BYTE)(c3))<<24)))

#### FileTimeToTime_t ####

void  FileTimeToTime_t(  FILETIME  ft,  time_t  *t  )  
{  
           ULARGE_INTEGER            ui;  
           ui.LowPart            =  ft.dwLowDateTime;  
           ui.HighPart            =  ft.dwHighDateTime;  

           *t            =  ((LONGLONG)(ui.QuadPart  -  116444736000000000)  /  10000000);  
}